I do not know how well you understand astrology, so first I have to ask if you have a "square" aspect because those two planets are between 82 and 98 degrees apart ... or if you are just basing this on the face that one planet is in Leo and the other in Scorpio.
Signs do not indicate aspects. Distances indicates aspects.
(example, if your Mars was at, say, 2 degrees of Leo, Pluto would ONLY be square to your Mars IF Pluto was between 24 Libra and 10 Scorpio).
So ... assuming this IS the case, that there actually is an aspect ... Mars square Pluto means that how you feel your desires and go after whatever it is you want ... and how you use your will-power ... clash with each other in ways that either create inner conflict and tension, or that cause you to behavior in ways that make it difficult to get/achieve what you wish.
More specifically, this makes you too forceful. And Mars being in enthusiastic stubborn Leo, with Pluto in intense and stubborn Scorpio, you don't know when to step back and "chill."
At least, not until you LEARN how to do this, and to recognize when it is appropriate to stop being so forceful.
Mars square Pluto, regardless of the signs these planets are in, is too aggressive in going after what you want. And you are often foolish/reckless. You may excuse your pushiness, finding reasons to justify it, and may believe you have a right to force things on others.
Of course, much depends on the REST of the chart. If the drives to be empathetic and gentle are at least as strong ans the Mars-Pluto aspect, then sometimes you are that way, and other times you are forceful.
And positive influences elsewhere in the chart can make it much easier for you to learn how to harness your strong energy/will, and use it for good 'causes', rather than just trying to get what you want.