Let's start with the first generally well-known circle beyond the nuclear family of parents and siblings: parents of your parents are your grandparents; children of your siblings are nieces and nephews; siblings of your parents are aunts and uncles; children of your aunts and uncles are first cousins.
Taking a peek next at the most direct line of the generations that precede us, we have greats and grands: your grandparents' parents are your great-grandparents; their parents are your great-great-grandparents, and so on. And just as your parents' siblings are aunts and uncles, so are your grandparents' siblings great-aunts (or grandaunts) and great-uncles (or granduncles), and your great-grandparents' siblings great-great-aunts and great-great-uncles, and so on.
还有一种cousins，叫first cousins once removed，“隔了一代的第一代表亲”又是什么意思呢？
First cousins once removed
The degree of a cousin (first, second, third, etc.) doesn't change between generations, but the word removed is used to signal a different generation. Your first cousin —let's say it's Sue— is also a first cousin to your own child, but is removed by a generation, making Sue your child's first cousin once removed.
表亲关系不管是一代、二代还是三代的，都不因为辈分变化而变化，而removed这个单词是用来表示两人不属于同一辈的情况。假设苏是你的第一代表亲，那么她也是你孩子的第一代表亲，但是这中间差了一辈，因此苏就是你孩子的first cousin once removed。