A stake is the amount of money you put at risk on a single bet or spin.
Stake size sets how fast a balance moves. It is also the base figure that wagering requirements, turnover and bonus contribution are calculated from.
A 2 euro spin on a slot is a 2 euro stake. Ten spins at 2 euro is 20 euro staked, even if the balance never drops by 20 because wins are returned along the way.
No. A deposit is money moved into the account. A stake is money placed on one bet or spin. One 50 euro deposit can be staked many times over.
Bonus funds staked usually count towards turnover and wagering requirements, but game contribution rates can reduce how much of each stake is counted. The bonus terms state the rate.