Hypertrophy — muscle growth
An increase in muscle fibre size, and so in the muscle. In gym talk, putting on size.
A muscle grows when it gets enough load, then food and sleep to recover. The main levers in the gym are volume (how many working sets per muscle a week), proximity to failure and progression: doing more over time.
On volume — more weekly sets give more growth on average, but with diminishing returns: that's what the Schoenfeld et al. (2017) meta-analysis found, and the newer Pelland et al. analysis too. Frequency on its own barely matters when the volume is the same: twice a week for 5 sets is about the same as once for 10. The rep range is wide: both 6 and 15 reps build muscle if the sets are close to failure.
The details, with numbers, are in the guide on sets per muscle per week, and exercises by group are in the muscles section.
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In the diary I work out all of these numbers myself — you just log the set.