The noun <em>clase</em> in Spanish means <em>class </em> in English. It is feminine, so the article coming before it is: LA.
la clase
(or <em>una clase</em> if it is undetermined)
To make it plural, we add an <em>-s</em> to the noun and also to the article.
clase + s = clases
la + s = las
<em>las clases</em>
<em />
In this example, we have the determined article before the noun <em>clases</em> because it is a determined kind of class: clases de ciencias (science classes).
