I have a list of words in a dictionary with the value = the repetition of the keyword but I only want a list of distinct words so I wanted to count the number of keywords. I
Calling len() directly on your dictionary works, and is faster than building an iterator, d.keys(), and calling len() on it, but the speed of either will negligible in comparison to whatever else your program is doing.
d = {x: x**2 for x in range(1000)}
len(d)
# 1000
len(d.keys())
# 1000
%timeit len(d)
# 41.9 ns ± 0.244 ns per loop (mean ± std. dev. of 7 runs, 10000000 loops each)
%timeit len(d.keys())
# 83.3 ns ± 0.41 ns per loop (mean ± std. dev. of 7 runs, 10000000 loops each)