This idiom or expression means:

The last part of something.
The final stage in a series of stages.
The final portion of a racetrack before the finish line.

“On the home stretch” could mean:
Going home; or
Almost finished; or
Getting close to destination; Etc.

A. Are we on the home stretch yet?
B. No, we still have a few things to do.

You need to know your limits.

This idiom or expression refers to:

A difficult thing.

When someone says “This is a reach for me,” they mean something like “It’s difficult for me to do something like this. I don’t think I can do it.”

Also:
A stretch.
Out of reach.