That’ll is defined as that will.
An example of that’ll are the expressions “That’ll do.” or “That’ll be all.”
- You really think that'll work on me?
- That'll give you more gas than the Hindenberg, Dean said but he couldn't be sure he was heard over the din of music and vacuum.
- "That'll do," she said to him then straightened.
- "It's not your hand that'll get you in trouble," Dean said as he munched on a piece of whole wheat toast.
- Maybe that'll give us a chance to talk to her.