A 121, or one-to-one meeting is a private meeting between a report and their manager.
It's a report's time to share their successes, blockers and seek advice: the agenda is theirs!
At Learnerbly, people have regular 121s with their manager
One-to-one meetings provide people with the time to discuss projects and goals with their manager, from how they're feeling to how they plan to develop.
Essentially, it's a time to address issues which are important but not urgent.
People usually have them weekly or bi-weekly, depending on the cadence that works best for them.