Many languages divide nouns into different genders. English has the remnants of a three gender system which determines the choice of pronoun (he, she, it, his, hers, its, etc.) and is usually related to the sex. In French, Spanish and Italian nouns are either masculine and feminine. In German there are three genders masculine, feminine and neuter. The way genders are assigned to nouns is largely arbitrary, and can be tricky.
In Italian it's easy to determine the gender of a noun: if it ends in 'o' it's masculine, if it ends in 'a' it's feminine, but if it ends in 'e' it could be either. In other languages there are a few rules you can use to determine gender, usually based on the endings of the nouns, but there are many exceptions to these rules.
One way to learn the gender of nouns is to visualize a familiar place, such as your home town, and to divide it into two, three or however many genders there are in your second language. Then picture nouns of one gender in one part of town and nouns of another gender in a different part of town.
Another way to memorize genders is to associate nouns with adjectives which change to show the gender. For example, plume petite (small feather) - feminine, arbre petit (small tree) - masculine.
Anyway, I hope this helped, and if not, please give me suggestions as to other ways you could remember the gender rules.