In biology, competitionis an interaction between multiple organisms within a community that all depend on the same limited resource. One species generally adapts to better access that resource and the other dies off, an example of natural selection.
Interspecies competition is when you have 2 groups of different species in the same area going after the same resource i.e. they're trying to occupy the same niche or niche as others call it. And what that means is if they're going for the same resources somebody's going to lose, and that's something called the competitive exclusion principle. They wind up going after the exact same resource in the exact same way. One of those species is going to die out, a good analogy for this is imagine you want to be captain of the football team and somebody else wants to be captain of the football team. There can only be one and eventually somebody is not going to make the cut. In the real world if you have two predators all going after the same rabbit for example eventually one of the groups of predator's going to be faster and able to catch the rabbit more often or maybe will have more babies and then in some way wind up out competing the other one.
Now sometimes a way to minimize this kind of overlap of your resources or overlap of your niches is to partition the resource. If you imagine there are some birds 2 different species of birds that are going after seeds let's suppose they're in force with a bunch of fruit trees and other things that are producing seeds. If one bird focuses at getting the seeds while there're still on the tree while the other one goes after the seeds from food that is falling and after the seeds of things like the grasses and bushes, then they can minimize the competition between them since they're both going after seeds but one is going from them in a higher regions of the force the other one is going for the lower regions.
This is one way that you'll see species competition being reduced in this way. This ultimately may lead to something called character displacement, if you give it enough time natural selection will start making differences appear between these 2 species. The bird that's going after the seeds that are up in the forest canopy since it's around the leaves it may require different protective coloration to hide it from predators, its beak may need to be modified to help penetrate the fruit while the one that's going on the ground if the food has already rotted away it can have a beak shape that's different and it'll need to have protective coloration for the plant growth that's around the base of the tree and these are the ways that you can have interspecies competition influencing the organisms in a particular area.