上百人在这个城市里无家可归.
several hundreds就和hundreds of一样,都是表示很多,上百的意思.hundred是一百,several hundreds就是几百喽,算是虚数吧.这句话里省略掉了people.如果完整的说就是several hundreds of people in the city have lost their house
类似的,可以有thousands of,hundred thousands of,several thousands of.都是表示很多的意思