个 is a measure word. It must be used if you are describing how many of something there is. There are many many measure words in Chinese, but usually 个 can be used in place of all of them. Obviously if you know more, you sound more native. English does have some equivalents. If you are talking about "tape" (like duct tape) you don't say "I need a tape". You say "I need a ROLL OF tape". "Roll" here is the measure word. For example, you would say "一个“ to mean "a" or literally "one of" something. You just need to get used to putting 个 between a number and a noun.

we have three main auxiliary word using “de” with same pinyin ,but different characters completely. They are "的，地，得“. 1) 的--美丽的花（beautiful follower)，大的城市(big city)，精彩的电影（excited movie), 的 is following by adjectives and make with other nouns to express what kind of shape, kind, color, good or bad that is looked like. sometimes, it is used to be in "of" with noun. But it is not necessary to translated directly into "的”，like a piece of paper, 一张纸，

2) 地--很快地跑 run fast/quickly，积极地准备 prepare actively，勇敢地跳跃 jump bravely . 地 is used for verbs as adverbs in how it is working on. But verb is the core or stress word as what you wish to express, not adjectives.

3) 得--跑得快 run fast/quickly，准备得积极 prepare actively，跳得远 jump vey long , here 得 is complement in transaction following only by verbs. It will give us how extent that you works on.

#1 个（gè) can be classifier eg. 一个好人 ；(gè) it also can be a objective, means single eg.个体 ;additionally (gè) can be used to measure size eg.高个儿 #2 的 (de) Auxiliary word eg.我的母亲 PS：的has other pronunciation such as (dí) and (dì) #3 了 (le) Auxiliary word, to emphasize an action is finished eg. 吃完了 PS:了has other pronunciation such as (liǎo)

个 there is no english equivalent. It's a classifier, we don't have this in the european languages. 了 is the conjugation in past tense, you put it after a verb, just like ypu add ED to a verb in english to turn it into past tense. 的 Expresses the possesion. Something belonging to an other thing. It is the equivalent of " of " or " ....'s " in english.

We actually do have English equivalent to 个。。。 a heard of cattle, a flock of sheep, a loaf of bread, a litter of cats... However, I think of 个 as the english equivalent to the word "a" and "an", except in chinese, they have many different characters that represent ("a" and "an") 只猫（a cat) 本书（a book) 张桌子（a table.)