A predicate is a word or a clause that explains or says something about the subject. The syllable 다 is a stem used on verbs and adjectives.

Verbs and adjectives basically have the same construction. Verbs normally signify actions and processes whereas adjectives(also called descriptive verbs) indicate the state or quality(i.e size, weight, length), quantity, shape, appearance, perception or emotion.

There are two types of stems, the vowel and consonant-based stems, which are pretty much self-explanatory.

Examples of vowel-based verbs are:
가르다 divide
가지다 have
가르치다 teach
만지다 touch
보다 see/look
가다 go
배우다 learn

and vowel-based adjectives:
시다 sour
싸다 cheap
쓰다 bitter
짜다 salty
크다 big
흐리다 cloudy
히다 white

When we say consonant-based, the word(without the syllable 다) ends with a consonant, and is usually an irregular word, which we will come to tackle deeper later on.

Some examples of consonant-based verbs are:
닫다 close
신다 wear(shoes)
받다 accept
살다 live
앉다 sit
읽다 read
팔다 sell

and consonant-based adjectives:
가볍다 light(weight)
가깝다 near
넓다 wide
많다 many
작다 small
좋다 good
뜨겁다 hot(object)

I purposefully used simple and commonly used words, and I hope this can also serve as vocabulary to you. :) This will serve somewhat like an introduction to verbs and adjectives. We will talk about it deeply later on, includ