This past weekend QGIS 3.6 Noosa was released as the next stable release. You can visit the QGIS download site to find installers for Windows, Mac and Linux.
At the same time QGIS 3.4 Madeira became the latest long-term release. This means that version 3.4 will be supported for a calendar year with bug fixes. This is now the version you should install and work with for the next year.
If you have not yet worked with the new 3.x line you can look at the visual changelogs here: Version 3.0 – Version 3.2 – Version 3.4. In general the QGIS 3.x line is a major upgrade from 2.x. I encourage you to install it and make a map!