Answer:
speciation is when one species splits off into multiple species.
In-depth answer:
Speciation can happen in 4 different ways, the first being Allopatric Speciation, where 2 groups of the same species are physically separated for extended periods of time, and when they're re-introduced, they don't breed.
Sympatric Speciation is when 2 groups of the same species aren't seperated, but form different behaviors that isolate them reproductively (the groups wont inter-breed)
Parapatric Speciation is when 2 groups of the same species are suddenly placed into a new environmental niche, and adapt in different ways to fill that niche.
Quantum Speciation is much less recognized, but it's when a new species rapidly evolves and 'buds off' from the original group