Bimonthly does mean that something occurs twice a month or every two months. There is no technical definition as it depends on the context. a) When it occurs two times in a month, usually it is said to be every other week since there are typically four weeks in a month. b) When it occurs every two months, it is usually said to be every other month which means that it skips one and goes to the next. Overall, with bimonthly, you typically would say every other week for twice within a month, and every other month for every two months. If you have any other questions, don't hesitate to ask!

Even when it happens twice a month, in certain contexts in American English we don't say it. For instance, if you get paid every two weeks, you say that you get paid "biweekly", not "bimonthly".