Talking about siblings.

Hi I was wondering if anyone can help me. I came across these words and I'm not sure what they mean. Does this mean I have 1 brother older than me? Or does it mean he is 1 year older than me? 兄は僕より一つ上 Same with this one here...I'm not too sure if it means 3 younger sisters or a younger sister thats younger than me by 3 years. 妹は僕より三つ下

Not sure if the sentence is quite correct, but if it is, then it definitely states that your brother is 1 year older than you. (counters such as: "一つ, 二つ、三つ..." are only used for objects). Same goes for the the second sentence. Your sister is 3 years younger than you are.

Hello Jackyさん、 As　コッドさん explained: 兄は僕より一つ上 means my brother is one year older but we would normally say: 兄は僕より一歳年上です。 歳＝さい　（Counter for age) 年上＝としうえ　（Phrase for older in age) Same for the 2nd example: 妹は僕より三歳年下です。 年下＝としした　（Phrase for younger in age)