それを理解するのは簡単ではない。

that (indicating an item or person near the listener, the action of the listener, or something on their mind); it; that time; then; there (indicating a place near the listener); you

indicates direct object of action; indicates subject of causative expression; indicates an area traversed; indicates time (period) over which action takes place; indicates point of departure or separation of action; indicates object of desire, like, hate, etc.

understanding; comprehension; appreciation; sympathy

indicates possessive; nominalizes verbs and adjectives; substitutes for "ga" in subordinate phrases; (at sentence-end, falling tone) indicates a confident conclusion; (at sentence-end) indicates emotional emphasis; (at sentence-end, rising tone) indicates question

topic marker particle; indicates contrast with another option (stated or unstated); adds emphasis

simple; easy; uncomplicated; brief; quick; light

be; is; indicates past or completed action; indicates light imperative

not; emphatic suffix