What does that mean ?

[giorg0s]

In the free picks section what does the -10 +10 etc mean ?
For example
buf pk +05 -> What is the +05 here ?
bos/atl under 5.5-20 -> THe -20

Thanks

 

[mendel2710]

-120 lay $120 to win $100
+105 lay 100 to $105

Just the last 2 numbers