how to tell if my mac has a 64-bit processor?

hello,

the mac app store says that to run catalina OS, the mac has to have an Intel 64-bit processor.

i ried to dig up this info for my macbook air mid-2012, but all i can find is:

1.8 GHz Intel Core i5.

do all macbook air mid-2012 have the Intel 64-bit processor?

how do i find out?

because i wish to update my OS from el capitan to catalina.

thanks!