Frequency tells you the pitch of sound. High frequency sound is high pitched, and low frequency sound is low pitched.
It is the distance between two notes which are next to one another in pitch. If two notes are as close as possible on the piano keyboard, the distance between them is a semitone.
Typically, cents are used to express small intervals, or to compare the sizes of comparable intervals in different tuning systems, and in fact the interval of one cent is too small to be heard between successive notes.