"Five point five" can be expressed in Engpsh as "five and a half".
The term "point" is commonly used in Engpsh to indicate a decimal point in a number, for example "five point five" means 5.5.
Examples:
"I need to reach the weight of five and a half stones."
"The cake is five and a half inches tall."
Translations:
"我需要达到五点五个石头的重量。"
"这个蛋糕有五点五英寸高。"