“Yeah, overall I'd say I am.”

Your friend has asked you whether you are satisfied with your job. There are some parts of your job that you don't like, but you like most of it. You say:

Yeah, overall I'd say I am.

yeah

This is a more casual way of saying "yes". Use it in spoken conversation when you don't need to sound too serious.

overall, (sentence)

You can use the word "overall" at the beginning or end of a sentence. It's used when your general opinion about something is different from your opinion about some of the specific parts of it. For example:

The Canon T2i has some weak points, but overall it's a great camera.

I'd say (clause)

This is how you answer a question or give an opinion, when you're not really sure:

I'd say she'll probably be back at about 2:00.