There are a lot of different themes going on in Shakespeare's Hamlet. 25 words is insufficient to cover all of them. Depending on who you ask, they might be able to list you five to ten different themes present in the play. With as few as five themes, that's only five words per theme explanation in your review. If all that you have to do is list the themes within the play, then 25 words could be possible. For example:
"A variety of themes are present in Hamlet. Some are less important to the plot, but several are absolutely integral. First, revenge is a major thematic driving force in the play. It is what motivates many of the characters to act the way they do. Tying in with the theme of revenge are the themes of lies and deception. These are the tools used by Hamlet to seek revenge, but other characters lie and deceive throughout the play as well."