Your expression is 3t^2+5t
A term in an expression is always separated by either a + or a - sign. We can see we have 1 + sign, so we know we have 2 terms.
The terms simply are: 3t^2 and 5t
NOTES:
If the letter is with the number, that counts as one term, not 2.
If you have a - sign, put it with the term.