There is euphemism/allusion to sexual/ marital rape
Many kisses between teens are shown. Nothing too bad
There is a kissing scene at the end of season 3
A Teen Boy Abuse A Girl By Touching Her Breast (clothes on)
No sex scenes, no nudity
Over the course of the series, there are implications made more than once about intimate relations, usually referring to an older married couple, but even sometimes referring to younger kids and their curiosity about the subject.
Sex is mentioned very briefly in a few scenes. A girl gets her first period and there is an episode focused on this.
There's a discussion about the facts of life using a mouse in a man's pocket as a metaphor that may be confusing for younger viewers. An episode is dedicated to Anne getting her first period.