Every French noun has a grammatical gender, masculine or feminine, which has nothing to do with real-world sex for objects and ideas — la table (the table) is feminine, le livre (the book) is masculine, for no reason beyond how the word has always been used. Gender determines the article, adjective endings, and pronoun choice, so it has to be learned along with the noun itself.
A noun's ending is a useful, though imperfect, hint. Endings like -tion, -sion, -ette, -ance, and -ence are almost always feminine (la nation, la chance), while -eau, -isme, -ment, and -age tend to be masculine (le bureau, le tourisme, le gouvernement). These patterns have real exceptions, so when in doubt, the safest approach is still to memorize a new noun together with its article.