N5
ので
Because, So, Since, The reason being
私は寿司が好きではないので、食べない。
I don't like sushi, so I don't eat it.
Explanation
「ので」 gives a reason, like 'because … so …': 「体調が悪いので、休みます」 (I'm not feeling well, so I'll take the day off). It presents the reason as an objective fact, which sounds gentle and polite, so people use it for asking leave, apologising, declining invitations and explaining to bosses and customers. Form: plain form of a verb or い-adjective + ので; noun or な-adjective + なので.
Mixed up with
「ので」 is objective and soft; 「から」 is the speaker's own claim and more direct.
After 「ので」 you normally do not put a command or prohibition: 「雨が降るのですぐ帰れ」 is unnatural; use 「から」. For a request or asking leave, 「〜てください」 and 「〜ていただけませんか」 are common.
After a noun or a な-adjective use 「なので」: never 「休みだので」 or 「静かだので」.