This is the 12581st most frequent Spanish word.
montarse
"Montarse" means "to get on" or "to ride."
In this sentence, 'montarse' is used to mean 'to get on' or 'to ride', specifically getting onto a bicycle.
El niño aprendió a montarse en bicicleta.
The child learned to ride a bicycle.
Here, 'montarse' is figuratively used to express joining or getting involved in something, like a project.
María quiere montarse en el proyecto para aprender más.
María wants to get involved in the project to learn more.
In this case, 'montarse' indicates physically climbing onto or getting on top of an object, like a table.