I am really struggling with this concept, please help. I know that the period is simply the time for 1 for one complete cycle, but how come the frequency is 1 over this? It is confusing to me
Let's clarify your definition of frequency first. Frequency is simply the number of oscillations a body performs in one second. Time period is the time taken for one complete oscillation. As you get 1 oscillation in T seconds, you get 1/T oscillation in 1 second.