It's a logic puzzle. Fill in the blank spaces the the keys.
The dots indicate whether the characters are correct (in terms of the answer), but are not indicative of position themselves.
The answer has six spaces, so there can only be six characters in it. That means only six characters across all of the characters in the clue are correct.
You should be able to start eliminating incorrect ones by logical inference.
For a big clue on this, the last word only has one character that's correct, and the position of that character is also correct. Since the first word in the set has five correct characters, it can be assumed that most (if not all) of the characters in the last word that are not in the first word are not correct and can be eliminated.
To demonstrate, the last word provided is this:
That means that one of the characters is both correct and in the correct place
Since the answer spaces are:
You can know that the correct character is n. That means that none of the other characters are correct.
If it was instead:
Then you would know that n was correct and in the right place, and that one of the other five characters was also correct but we wouldn't know which one. We know that n is correct and in the right place because it is provided for us as an additional hint.
It's difficult to explain in a different way than yoda did already but I'll try. You have one letter of the answer and the keys and clues are telling you about letters in the clue words which exist in the answer word. The solid dots indicate a correct letter in a correct position, but not which position those letters are in. The hollow dots are correct letters in incorrect positions, but again don't tell you which letter or where it is. You have to figure that out by logical deduction. notify has 1 right letter in the right position. The answer word has an n already filled in. So that's your one given answer, work back from there.
The last word has one letter in the right position, which is the first letter written in the answer ... so the rest of the letters in the fifth word cannot be used and can be eliminated from the other words ... if you continue with such logical deductions, you will find the answer.