Service Battery Symbols

My mac has been running out of battery very quickly when I take it out at 100%, and my laptop dies at 40-50% of battery life still left.

I don't know If I'm right, but does this mean I need to replace the computer's battery with a new one and get it done at an Apple Services shop? Or if possible Is there a way I can do It myself, as I suspect It would be cheaper. Though It might be too complex for me. I do have an AppleCare on this laptop and Its only been 2 years from when I got this laptop, so it has not expired as of yet.

And I'm also wondering if this warning symbol has something to do with my laptop's battery running out so quickly.

Here is what is looks like:

Thank you! :D