The singular and plural forms are indistinguishable, both in spelling and pronunciation : 'un cours' (singular) and 'des cours' (plural). However, you can rely on context and the grammar of other words in the sentence to tell you whether you're talking about one or several lessons.

Un cours et des cours. Un repas et des repas Ce repas est très délicieux. Ces repas sont très délicieux. Bonne chance

yes.