Such an equation (that can be written $P(x,y)=0$, where $P$ is a polynomial) is called an algebraic equation. The field devoted to understanding the solutions of such equations is called algebraic geometry.
(In the case of just one equation and two variables like your example, the set of solutions is called an algebraic curve).
It is not the case that every such equation has a specific name (since there are infinitely many of them), but there is a partial classification of such equations (though it would be hard to formulate in simple terms if you're not familiar with differential geometry or algebraic geometry).