The first line starts with curl and first shows the main version number of the tool. Then follows the "platform" the tool was built for within parentheses and the libcurl version. Those three fields are common for all curl builds.
If the curl version number has -DEV appended to it, it means the version is built straight from a in-development source code and it is not an officially released and "blessed" version.
The rest of this line contains names of third party components this build of curl uses, often with their invidual version number next to it with a slash separator. Like OpenSSL/1.1.1g and nghttp2/1.41.0. This can for example tell you which TLS backends this curl uses.
Line 1: TLS versions
Line 1 may contain one or more TLS libraries. curl can be built to support more than one TLS library which then makes curl - at startup - select which particular backend to use for this invoke.
If curl supports more than one TLS library like this, the ones that are not selected by default will be listed within parentheses. Thus, if you do not specify which backend to use use (with the CURL_SSL_BACKEND environment variable) the one listed without parentheses will be used.
Line 2: Release-Date
This line shows the date this curl version was released by the curl project, and it can also show a secondary "Patch date" if it has been updated somehow after it was originally released.
This says [unreleased] if curl was built another way than from a release tarball, and as you can see above that's how Microsft did it for Windows 10 and the curl project does not recommend it.
Line 3: Protocols
This is a list of all transfer protocols (URL schemes really) in alphabetical order that this curl build supports. All names are shown in lowercase letters.
As of curl 7.71.1 this list can contain these protocols: