what does this mean "He that a a fool doth very wisely hit Doth very foolishly, although he smart, Not to seem senseless of the bob; if not, The wise man's folly is anatomized even by the squandering glances of the fool."

Jacques means that those things he jokes about (sins that many are guilty of) must be ignored by his listeners because if they pay attention or are hurt by those things he makes fun of, they concede that they're the subject of his jest. Thus, they expose themselves in regards to something that just might no be true but may seem true.