yankees
 

can someone tell me what year this is?

Early 1960s. Al Downing was brought up in 1961, and Johnny Sain was let go as pitching coach after 1963. Someone with more knowledge of those years and a better chiropractor than mine could probably narrow it down further.

What does the mark at the lower left say?

It looks like a mark either identifying the printer, or a union mark. Both of those sometimes have a code that can indicate the date, and occasionally how many were made.

Steve B