i'm going to explain this in english
first,it's 'ALWAYS' NOT 'aways' that's not a word...
second,understand i hope u know what it means,it means to know the meaning of.
i can't always understand,that means:sometimes,i can't understand.
so the whole sentence is like:when ppl(people) talk to me,sometimes i can't understand.
i recommand English translation is better for u,try to understand,it's a easy sentence.