Like the b command, the e command is a move command.
The e command moves forward to the end of a word.
If you are already at the end of a word, it will move to the end of the next word.
If you're say in the middle of a word, it will move to the end of that word.
The Capital E Command does exactly the same, but it includes special characters like a comma or period, so if a word ends in of those characters, it will move the cursor up to that character.
Note: Like the b command it ignores the under_score character.
Many key commands can be used with a [count]. If you been using the help docs in Vim, you'll see that the move commands like b and e have a [count] in the description. What this means is that you can do something like:
And this means it will move to end of of a word by 2. If you do 5e it will move by five words.