Like / Dislike: With these buttons you can add a like (or dislike) to the posting as quick reaction. The dislike button will only be shown, if the Dislike-feature is active for your account.
Comment: To add a comment to the posting hit this button, the comment editor will then be opened.
Reshare: The reshare feature will send the posting as it is to your followers. The original author will be notified about you resharing their posting. Note: The reshare will be handled native with the protocol the posting arrived in your stream. This means, postings from Diaspora* will only be shared with that network, while postings from an ActivityPub enabled platform will be shared with all your followers in these platforms.
Quote Share: This will open the editor for new postings, with a quote of the posting in it. You can now comment on the posting. When publishing the quoted share, a new posting will be created, so all your followers independent of their used platform, will receive your posting,
For events you have the special interaction buttons to signal you are attending, not attending and maybe attending to the event.
The last item in the button row is a checkbox. With this you can select multiple posting from your network stream to bulk delete all checked postings.