Now remember that in Spanish nouns, articles, and adjectives have gender and number; this means that the table, la mesa, the article "la" is feminine, "mesa" is feminine too. And, for example, el carro, the car, "carro" is a masculine noun and el, the, is a masculine article.
When we talk about number what we mean is plural or singular, just like in English we have car and cars, well in Spanish we also have carro and carros.
Alright let us see how this concept works in full phrases. Let us start with masculine nouns. El actor es elegante, the actor is elegant. El taco es delicioso, the taco is delicious. El hotel es moderno, the hotel is modern. El tren es necessario, the train is necessary.
"El" in the beginning of the sentence means 'the' as in the train and this word, "el," is only used for masculine singular words. For instance, I cannot say the trains with this word "el." El actor, el diccionario.
Let us repeat; el actor es elegante. El taco es delicioso. El hotel es moderno. El tren es necessario.