The commands for movement in the calendar buffer parallel the commands for movement in text. You can move forward and backward by days, weeks, months, and years.
The day and week commands are natural analogues of the usual Emacs commands for moving by characters and by lines. Just as C-n usually moves to the same column in the following line, in Calendar mode it moves to the same day in the following week. And C-p moves to the same day in the previous week.
The commands for motion by months and years work like those for weeks, but move a larger distance. The month commands M-] and M-[ move forward or backward by an entire month's time. The year commands C-x ] and C-x [ move forward or backward a whole year.
The easiest way to remember these commands is to consider months and years analogous to paragraphs and pages of text, respectively. But the commands themselves are not quite analogous. The ordinary Emacs paragraph commands move to the beginning or end of a paragraph, whereas these month and year commands move by an entire month or an entire year, which usually involves skipping across the end of a month or year.
Each of these commands accepts a numeric argument as repeat counts. For convenience, the digit keys and the minus sign are bound in Calendar mode so that it is unnecessary to type the M- prefix. For example, 100 C-f will move point 100 days forward from its present location.