Pinyin letters d, t, n, and l represent four more sounds pronounced similarly to sounds in English.
The trick to remembering the 2nd and 4th tone is to think of them as rising (2nd) and falling (4th).
In English, we say I am good or She is happy, but in Chinese you don’t use words like am or is before adjectives. Instead, adjectives are usually preceded by 很 (hěn). Sometimes 很 means very, but it’s more often just a way to connect a noun and an adjective.
In English, we can say I am happy, too or I’m also happy, but in Chinese the word for also or too (也) always comes before the adjective.