Adverb of frequency tells us how often something is happening. Adverb of frequency that describes definite frequency like weekly, daily, or yearly. An adverb describing indefinite frequency doesn’t specify an exact time frame; words like sometimes, often, and rarely are adverbs of frequency.
Examples of adverbs of frequency:
1) Every day (often)
2) Every week (sometimes)
3) Every month (sometimes)
4) Every year (always)
Here are the most important things to remember when using adverbs of frequency:
1) Use an adverb of frequency only when you're talking about the frequency with which something happens—not the ‘intensity’ of it.
For example, "Sometimes I get up early on Mondays." doesn't mean that it's common for me to wake up early on Mondays, but rather that I wake up early on Mondays in general. In this case, "often" would be an appropriate adverb of frequency. The sentence will be- I often get up early on Mondays.
2) Be careful not to confuse these with adverbs of degree, which show how intense something is. For example, "The students always showed up late" doesn't mean that students always show up late; instead, it means that students always do so without fail. In this case, "always" would be an appropriate adverb of degree.