improve explanation on Java array .length property

Author: melonpan

exercises/concept/bird-watcher/.docs/introduction.md

@@ -46,7 +46,8 @@ int secondElement = twoInts[1];
 Accessing an index that is outside of the valid indexes for the array results in an `IndexOutOfBoundsException`.
 
 Arrays can be manipulated by either calling an array instance's methods or properties, or by using the static methods defined in the `Arrays` class (typically only used in generic code).
-The most commonly used property for arrays is its length which can be accessed like this:
+The `length` property holds the length of an array.
+It can be accessed like this:
 
 ```java
 int arrayLength = someArray.length;