Since has two common uses in English, and context tells you which one is meant.
First, since can mean because. In this use, it gives a reason. For example: Since it was raining, we stayed inside. You can usually replace since with because and keep the same basic meaning.
Second, since can show a starting point in time. For example: I have lived here since 2020. Here, it does not mean because. It tells you when something began.
- Reason: Since you are here, let us begin.
- Time: She has felt better since Monday.
A quick way to check the meaning is this: if you can replace since with because, it is showing reason. If it answers when from, it is showing time. Both uses are common, so looking at the full sentence is important.
