Adjectives that end in 'o' are masculine. They must agree with the noun they describe, in number and gender. If an adjective is describing a group of items that contain a mix of genders, the masculine adjective is used.
The feminine version of the adjectives are formed by changing the ending 'o' to an 'a'.
Adjectives that end in 'e' are used for both feminine and masculine nouns. Add an 's' to make them plural.
Adjectives that end in consonants are used for both feminine and masculine nouns. Add an 'es' to make them plural.