Rate my first python prime checker
I'd have to rate your program a "D-Minus".


incorrectly labels 1, 0, and all negative numbers as prime!
runs in \$O(n)\$ time, instead of \$O(\sqrt n)\$ time
runs in \$O(n)\$ space, instead of \$O(1)\$ space


Other deficiencies:


'''docstrings''' should be used for describing "how" to use the module/class/method; comments should be used to explain how the code works
variable names are cryptic; too short to be descriptive
PEP8 guidelines are not consistently followed.  Operators like = should have 1 space on each side.  No space should be used after (, or before ), as well as not before :
a dictionary is being used to store a list of values; a simple list would suffice
dl.values() is an iterable; there is no need to convert it into a list in order to use in the for z in ...


As suggested by aaaaa says reinstate Monica,
please work on your solution and then submit it as a new question.