Reviewing other people's code

Reviewing other people's code is something you can do from your first month, even when the author is senior. Start by understanding the goal from the description and ticket. Then read for correctness, edge cases, tests and readability.

Ask questions when you do not understand; "what happens if this list is empty?" is a useful review comment. Be specific and kind, say whether each point blocks the merge, and mention what is good too. A simple labelling habit makes your intent clear, especially in a second language: start a comment with question, suggestion or issue, and add blocking or non-blocking. Reviewing also teaches you the codebase quickly.