The phrase "every other day" describes something that:

• happens one day
• doesn't happen the next day
• happens again the next day
• doesn't happen again the next day

...and so on.

You can use "every other ___" with any unit of time:

I get paid every other week.

I usually visit them about every other year.

You can also use this phrase to talk about something that happens "a lot":

He keeps interrupting me every other minute to ask me stupid questions.