Not much. They don't do anything. The one that looks like a speech bubble is for making x number of comments. The "@" one means someone has tagged you in a post. The heart one means your posts have been liked x number of times. The check mark one means you commented on a post that was created as a question and the person who asked the question marked your comment as an answer. The cake is an anniversary badge that you get after one year as a member.
All the ones that have numbers on them (comments, likes, anniversary) have the number increasing as you reach certain milestones. I don't remember the exact numbers but you'll get the comment badge after 10 comments, and then the 1 will appear above it after 50 and the 2 after 100 and the 3 after 1,000 or something like that.
Re: What do the badges..
Due: 6 Nov 2021
All the ones that have numbers on them (comments, likes, anniversary) have the number increasing as you reach certain milestones. I don't remember the exact numbers but you'll get the comment badge after 10 comments, and then the 1 will appear above it after 50 and the 2 after 100 and the 3 after 1,000 or something like that.
Due: 6 Nov 2021