1. to meet in a location between the person speaking and the person he/she is meeting
This way both have to travel less: ideally, each travels half the distance. 
my house*———->meeting place<———-*your house
2. to compromise
Each person gets something he/she wants.
I want to pay $500 for a job, and I want the work done in one week. 
You want to be paid $1000, and you want three weeks to do the work.
If we meet each other halfway,
I pay $750, and you have two weeks to finish. or
I pay $1,000, and you have one week to finish. or
I pay $500, and you have three weeks to finish.