The meaning is expressed by the link relation, see <https://news.ycombinator.com/item?id=32155744>.

> Is one of those links a link to delete the object I am viewing and one of them a link to update it?

Sure, see RFC 5023 § 11.1.

> What about the link to get a list of all the foos associated with this particular bar?

Okay, custom link relations since the existing predefined ones are insufficient. Because `foo` and `bar` are vague, I have to make up some details and can show one way to do it:

    GET /bar/this-particular HTTP/1.1
    Host: munk-a.example

    HTTP/1.1 200 OK
    Link: </ns-rel/bar>; rel="type"
    Link: </collection/foo?filter=/bar/this-particular>; rel="/ns-rel/foo"; title="list of all the foos associated with this particular bar"
    Link: </bar/this-particular>; rel="self"
    Link: </collection/bar>; rel="collection /ns-rel/bar"; title="list of all bars"
    Content-Type: application/octet-stream
    …

    GET /collection/foo?filter=/bar/this-particular HTTP/1.1
    Host: munk-a.example

    HTTP/1.1 200 OK
    Link: </ns-rel/foo>; rel="type"
    Link: </foo/some>; rel="item /ns-rel/foo"; title="some foo"
    Link: </foo/another>; rel="item /ns-rel/foo"; title="another foo"
    Link: </collection/foo?filter=/bar/this-particular>; rel="self start"
    Link: </collection/foo?filter=/bar/this-particular;page=2>; rel="next"
    Link: </collection/foo?filter=/bar/this-particular;page=11>; rel="last"
    Content-Type: multipart/mixed
    …

I'm skipping over the rant in the second paragraph which is clearly based on misunderstanding of the subject matter. Instead of baseless assertions, stick to asking questions if you don't want to make HN readers think you're an ignorant fool.