Bearing Burdens

Galatians 6:2 NASB
Bear one another's burdens, and thus fulfill the law of Christ.

This is a short verse with a lot to say, so today let's concentrate on the first part of this verse:
Bear one another's burdens . . .

To whom is Paul addressing this command?
What are they to be doing for each other?
How does this first part of the verse relate to what Paul said in the previous verse?

What does "bear" mean?
I looked up "bear" in Strong's, and it's number is G941. The Greek word is "bastazo," and it mean (literally or figuratively) to lift.
What are "burdens"?
It's Strong's number is G922. The Greek word is "baros," and it means weight.

What is weighing down this brother in Christ whom we who are spiritual are called to restore?
What are those who are spiritual supposed to do with our brother or sister's burdens?
And how are we to lift them? (See Galatians 6:1.)
By lifting them, what are we doing for our sister or brother in Christ?