What is map for in lambda code example

Example 1: map function using lambda in python

# Map function 

nums1 = [2,3,5,6,76,4,3,2]
sq = list(map(lambda a : a*a, nums1))
print(sq)

Example 2: python array find lambda

lst = [1,2,3,4]
filter(lambda x: x % 2 == 0, lst)
[x for x in lst if x %2 == 0]
#[2,4]