Mesh size - [dx dy]. This defines how fine is the discretised mesh. In general a finer mesh will be generate more accurate results, and will take longer to compute.
These are dampening factors used with coupling algorithms. The purpose is to avoid diverging solution for steady state simulations. The values mentioned below for SIMPLE algorithm are advised by renowned CFD authors like Peric, Roy Chowdhury, Versteeg & inventor of SIMPLE algorithm Mr. Suhas Patankar.
It's advised to check multiple values for best Residual behavior.