Something about the idea of Molarity is confusing me Okay, so molarity is defined as moles of solute per liter of solution. It is used to describe the concentration. So in the lab, when I see a bottle labeled something like $\mathrm{3.5~M}~\ce{H2SO4}$, is it saying that the only chemical in the bottle is this $\ce{H2SO4}$? 

Because the way I think of it is "there are 3.5 moles of $\ce{H2SO4}$ per liter of solution". The word "solution" is kind of throwing me off because it makes me feel like they are saying that there is more than just $\ce{H2SO4}$ in the bottle. Correct me if I'm wrong, but don't you need at least 2 solutes to make a solution? 

I don't know why I'm having such a hard time grasping this. But any help would be awesome!
Correct me if I'm wrong, but don't you need at least 2 solutes to make a solution?


You are, unfortunately, incorrect. In wet chemistry, you need just a solvent$^\dagger$ and at least one solute to make a solution.  While this does mean that you need at least two constituents to make up a solution, you do not need at least two solutes.


  ... is it saying that the ONLY chemical in the bottle is this $\ce{H2SO4}$?


It depends on your definition of a chemical:


If you consider water to be a chemical, then no: there are two chemicals in the bottle$^\ddagger$, $\ce{H2O}$ and $\ce{H2SO4}$.
If you are not considering water to be a chemical, then yes: the only chemical in the bottle$^\ddagger$ is $\ce{H2SO4}$.


$^\dagger$ If not specified, the solvent is almost always water.

$^\ddagger$ Except for small amounts of inevitable impurities.