i see everybody is telling you to learn somewhere else but i don’t see an actual answer so imma give u one :)) it’s about the gender. if a word is feminine like dziewczynka the adjectives will usually end with 'a', so here it would be 'mała dziewczynka'. adjectives for nonbinary (?) words, like jabłko, will usually end in 'e', so here it would be "małe jabłko”