"The woman eats rice."
Translation:La mujer come arroz.
Use "come" for 3rd person singular (él/ella come, that is, he/she eats) and "comen" for the same in plural (ellos comen, that is, they eat). Note however that the formal "you" (usted/ustedes) use these forms as well: usted come / ustedes comen.
I forgot the other persons: yo como / tú comes / nosotros comemos / vosotros coméis. That is, I / you / we / you eat.
nope. "The woman eats it" would be "La mujer lo come." You can only attach object pronouns to the end of infinitives or participles, not conjugated verbs.
It's not wrong. But maybe you used it in the wrong person ("él come" vs. "ellos comen")