Losing your serve is when you lose the game in which you were serving, it is said the oppenent (whoever that may be) broke someones (whoever was servings) serve. If you win the game then you held your serve.
Fault
Sports where you serve a ball include tennis, volleyball, badminton, table tennis, and pickleball. In tennis, the serve starts each point, while in volleyball, the serve initiates play and is crucial for scoring. Badminton and table tennis also require a serve to start each rally, and in pickleball, the serve is used to begin each point as well.
For a given play, there is only one service unless there is a "let" (ball touches the net or opponent not ready). A failed service is a point for the opponent. This is different from tennis where a service fault allows another serve.
You can hit an underhand serve in tennis; however, the overhand serve is more effective because it is more powerful. That is why you don't see the underhand serve used much.
a serve
Badly.
A tennis ball!
It depends on how hard you want to hit the ball
a tennis ball
Let
Yes
A tennis ball.