Most adjectives usually come after a noun but the singular masculine adjectives bueno (good) and malo (bad) have special short forms - buen and mal - which can be used before the noun. They have a slightly stronger meaning when used like this.
See and listen to these examples:
Similarly, grande (big), has a short-form gran which can also be used before the noun. Unlike buen and mal, gran can also be used with feminine nouns.
Gran has a more figurative meaning of great or fantastic when used like this.
NB: The plural forms stay the same even if used before the noun. For example:
See also Position of adjectives in Spanish.
Examples and resources
Q&A Forum 2 questions, 2 answers
My dictionary says 'hran' is only before masculine nouns, but you say m&f. Is there a difference in dialects? Got it wrong using dictionary.
"Gran" can be placed before a masculine or feminine noun, for example "un gran hombre" or "una gran mujer". It is different to other short forms like "buen" where you can only place it befor a masculine noun, not a feminine noun, for example "un buen hombre" but "una buena mujer".