Reblog
Reblogging means that you share the content of someone else with your followers. To your followers it almost looks like you would have posted it. Reblog content from within your niche to feed your followers with even more great content. Also, the person you reblogged from might decides to reblog your content as well. Helping your blog thereby to get in front of their followers and so on.
When reblogging you can also write your own text, e.g. write something funny about the picture or write a short story about what you would do with that chick 😉 You can also come up with your own tags for the content.
Tumblr?s limit is 250 daily posts and reblogs, so the reblogs are counted the same way as original posts.