diff --git a/docs/api/dt/corr.rst b/docs/api/dt/corr.rst
index ba6cddca3e..aa5eef3b90 100644
--- a/docs/api/dt/corr.rst
+++ b/docs/api/dt/corr.rst
@@ -11,7 +11,7 @@
 
     Parameters
     ----------
-    col1, col2: Expr
+    col1, col2: FExpr
         Input columns.
 
     return: Expr
diff --git a/docs/api/dt/count.rst b/docs/api/dt/count.rst
index dfdb6a9394..a21e38440d 100644
--- a/docs/api/dt/count.rst
+++ b/docs/api/dt/count.rst
@@ -9,7 +9,7 @@
 
     Parameters
     ----------
-    cols: Expr
+    cols: FExpr
         Input columns.
 
     return: Expr
diff --git a/docs/api/dt/countna.rst b/docs/api/dt/countna.rst
index 3c1c01cc14..078b4bb145 100644
--- a/docs/api/dt/countna.rst
+++ b/docs/api/dt/countna.rst
@@ -11,7 +11,7 @@
 
     Parameters
     ----------
-    cols: Expr
+    cols: FExpr
         Input columns.
 
     return: Expr
diff --git a/docs/api/dt/cov.rst b/docs/api/dt/cov.rst
index f253f9e99d..88d74f80e6 100644
--- a/docs/api/dt/cov.rst
+++ b/docs/api/dt/cov.rst
@@ -11,7 +11,7 @@
 
     Parameters
     ----------
-    col1, col2: Expr
+    col1, col2: FExpr
         Input columns.
 
     return: Expr
diff --git a/docs/api/dt/first.rst b/docs/api/dt/first.rst
index aea0145ae5..275467e6a5 100644
--- a/docs/api/dt/first.rst
+++ b/docs/api/dt/first.rst
@@ -11,7 +11,7 @@
 
     Parameters
     ----------
-    cols: Expr | iterable
+    cols: FExpr | iterable
         Input columns or an iterable.
 
     return: Expr | ...
diff --git a/docs/api/dt/last.rst b/docs/api/dt/last.rst
index 040a6f0fa8..049715c20a 100644
--- a/docs/api/dt/last.rst
+++ b/docs/api/dt/last.rst
@@ -11,7 +11,7 @@
 
     Parameters
     ----------
-    cols: Expr | iterable
+    cols: FExpr | iterable
         Input columns or an iterable.
 
     return: Expr | ...
diff --git a/docs/api/dt/max.rst b/docs/api/dt/max.rst
index 47eec0fb3b..b645de860b 100644
--- a/docs/api/dt/max.rst
+++ b/docs/api/dt/max.rst
@@ -11,7 +11,7 @@
 
     Parameters
     ----------
-    cols: Expr
+    cols: FExpr
         Input columns.
 
     return: Expr
diff --git a/docs/api/dt/mean.rst b/docs/api/dt/mean.rst
index 012381c25d..5377af8218 100644
--- a/docs/api/dt/mean.rst
+++ b/docs/api/dt/mean.rst
@@ -13,7 +13,7 @@
     cols: FExpr
         Input columns.
 
-    return: FExpr
+    return: Expr
         f-expression having one row, and the same names and number of columns
         as in `cols`. The column stypes are `float32` for
         `float32` columns, and `float64` for all the other numeric types.
diff --git a/docs/api/dt/median.rst b/docs/api/dt/median.rst
index 284f40081f..61eac12c42 100644
--- a/docs/api/dt/median.rst
+++ b/docs/api/dt/median.rst
@@ -10,7 +10,7 @@
 
     Parameters
     ----------
-    cols: Expr
+    cols: FExpr
         Input columns.
 
     return: Expr
diff --git a/docs/api/dt/min.rst b/docs/api/dt/min.rst
index 16d5f02be5..8c82deeaa0 100644
--- a/docs/api/dt/min.rst
+++ b/docs/api/dt/min.rst
@@ -15,7 +15,7 @@
     cols: FExpr
         Input columns.
 
-    return: FExpr
+    return: Expr
         f-expression having one row and the same names, stypes and number
         of columns as in `cols`.
 
diff --git a/docs/api/dt/nunique.rst b/docs/api/dt/nunique.rst
index e7705f202f..8f80d3612d 100644
--- a/docs/api/dt/nunique.rst
+++ b/docs/api/dt/nunique.rst
@@ -11,7 +11,7 @@
 
     Parameters
     ----------
-    cols: Expr
+    cols: FExpr
         Input columns.
 
     return: Expr
diff --git a/docs/api/dt/prod.rst b/docs/api/dt/prod.rst
index 9429c90738..4f90fafc33 100644
--- a/docs/api/dt/prod.rst
+++ b/docs/api/dt/prod.rst
@@ -15,7 +15,7 @@
     cols: FExpr
         Input columns.
 
-    return: FExpr
+    return: Expr
         f-expression having one row, and the same names and number of columns
         as in `cols`. The column stypes are `int64` for
         boolean and integer columns, `float32` for `float32` columns
diff --git a/docs/api/dt/rowlast.rst b/docs/api/dt/rowlast.rst
index e19de9a8a0..55a4e3e2e3 100644
--- a/docs/api/dt/rowlast.rst
+++ b/docs/api/dt/rowlast.rst
@@ -11,10 +11,10 @@
 
     Parameters
     ----------
-    cols: Expr
+    cols: FExpr
         Input columns.
 
-    return: Expr
+    return: FExpr
         f-expression consisting of one column and the same number
         of rows as in `cols`.
 
diff --git a/docs/api/dt/sd.rst b/docs/api/dt/sd.rst
index e4e7cf8e8e..ab6ab76f0f 100644
--- a/docs/api/dt/sd.rst
+++ b/docs/api/dt/sd.rst
@@ -12,7 +12,7 @@
     cols: FExpr
         Input columns.
 
-    return: FExpr
+    return: Expr
         f-expression having one row, and the same names and number of columns
         as in `cols`. The column stypes are `float32` for
         `float32` columns, and `float64` for all the other numeric types.
diff --git a/docs/api/dt/sum.rst b/docs/api/dt/sum.rst
index 494c1505ec..23ea9e0570 100644
--- a/docs/api/dt/sum.rst
+++ b/docs/api/dt/sum.rst
@@ -11,7 +11,7 @@
 
     Parameters
     ----------
-    cols: Expr
+    cols: FExpr
         Input columns.
 
     return: Expr