It means that you’re plugging in larger and larger x-values (i.e. x-values that are getting closer and closer to infinity) to see what happens. Limits answer the question “Which number did this function get to?” as well as “Which number did this function try to get to?”. In ...
Not a function: “one to many“. In other words, let’s say you had one x-value that maps to many y-values. For example, — in coordinate notation — (2,1) and (2,10). If the first number (the x-value) repeats, then you do not have a function. To put that another way, ...