Genus der Substantive

Every Spanish noun is either masculine or feminine, not just nouns for people. A table is feminine (la mesa), a book masculine (el libro), and there is no neuter "it" category for nouns. Gender is not about meaning, so thinking about the thing will not tell you; but the ending of the word gives it away most of the time.

The exceptions worth learning now

• el día - the day, masculine despite the -a: buenos días
• el mapa - the map
• la mano - the hand, feminine despite the -o
• la foto, la moto - short for la fotografía, la motocicleta, so they keep the feminine
• la radio - same story

The -ma words that are masculine (el problema, el sistema, el clima, el idioma) mostly come from Greek. Plenty of everyday -ma words are feminine as usual: la cama (bed), la forma, la crema catalana.

Words ending in -e or a consonant can go either way: el coche, la calle, el café, la leche, el pan, la sal. For these, learn the article with the noun, always as a pair: not "calle = street" but "la calle = street".

People and animals

For people, gender usually follows the person, and many words switch -o to -a or add -a: el amigo / la amiga, el profesor / la profesora, el camarero / la camarera. Words in -ista and -nte often stay the same and only the article changes: el / la periodista, el / la estudiante.

Why it matters

Gender is not decoration: the article and every adjective follow it. El piso nuevo but la casa nueva. A wrong gender is rarely a barrier to being understood, but it is the error native speakers notice first. English speakers, used to nouns with no gender, tend to guess from meaning (a dress must be feminine? el vestido is masculine). Trust the ending, and memorise the article for the rest.