diff --git a/docs/user-guide/concepts/expressions.md b/docs/user-guide/concepts/expressions.md
index add9e03d560b..9b857bb90aa0 100644
--- a/docs/user-guide/concepts/expressions.md
+++ b/docs/user-guide/concepts/expressions.md
@@ -21,7 +21,13 @@ Polars performs these core data transformations very quickly by:
 - automatic query optimization on each expression
 - automatic parallelization of expressions on many columns
 
-Polars expressions are a mapping from a series to a series (or mathematically `Fn(Series) -> Series`). As expressions have a `Series` as an input and a `Series` as an output then it is straightforward to do a sequence of expressions (similar to method chaining in pandas).
+An expression is a tree of operations that describe how to construct one or more
+Series. As the outputs are Series, it is straightforward to
+apply a sequence of expressions (similar to method chaining in pandas) each of which
+transforms the output from the previous step.
+
+If this seems abstract and confusing - don't worry! People quickly develop an intuition for expressions
+just by looking at a few examples. We'll do that next!
 
 ## Examples