You can easily understand this by knowing first the different actions of the plates depending on type of boundary:
Convergent - Ocean trenches and mountains
Divergent - Ocean ridges and rift valleys
Transform - tremors and earthquakes
Convergent boundary converge so that means meeting. So the plates meet each other or collide. When this happens, a couple things can occur. One plate slides under the other so that creates trenches. Or they can move upwards if they are as heavy as each other, which creates mountains.
Divergent boundary diverge, so that means to spread apart. So the plates are moving away from each other. So you can expect that ridges are formed like our ocean ridges. As they move apart they can create gaps in between.
Transform boundary is a bit different. Transform boundary is a process where the slides against and past each other horizontally. You need to get that these plates are heavy and so as they grind against each other, they shake, so you can expect earthquakes and tremors.