There are three kinds of extra hints to help you complete Acrostic puzzles:
1 - Vowel and Consonant shading
You will spot that within the puzzle grid that some of the cells are shaded differently. The pale blue squares are spaces for consonants, and the pale pink squares are spaces for vowels. These can help you get a sense of the shape of the word!
You can turn off this feature in the options
2 - Magic Reveal
Every time you get a horizontal word correct, the shared letter that crosses the vertical word gets revealed throughout the rest of the puzzle. Each extra word you get will usually give you more clues in the rest of the puzzle and make it easier as you go along.
If you get the target word, then all of the letters in the target word get magically revealed in the rest of the puzzle.
Again, if you prefer more of a challenge, you can turn this feature off in the game options.
3 - Bookend Hints
When you ask for a hint in Acrostic (by tapping the '?' icon in the side bar) it will give you the bookend letters - the first and last letter - and fix them in place. This is often enough to give you enough of a hint that you can guess the rest of the word straight away, but if you need more help, tap hint again and it will give you the next letters in from each end.
It'll never give you the crossing letter though - you'll have to figure that out for yourself!
These hints add a small time penalty (30 seconds) each time you use them, which will add to your final time for the daily puzzles. There's no limit to how many hints you can ask for but to get the best possible times, it's best to try to get each word using no more than one hint, otherwise it'll add up to extra minutes onto your time!