How do I make sure not to exceed the characters count?

This is how you can count the characters in each column within your feed

In each column in your feed, you can open the Statistics:

You can search for a specific value in the upper search bar.

1. Distinct - Number of Distinct values

2. Count - Number of Total values

Click on the Length to organize data from longest to shortest: 

NOTE: When including dynamic values in your ad's headline or description, you must consider Google's character's count.  Headline can contain up to 30 characters and Descriptions up to 90 characters.