To save a layer to your device select in the main menu Layer ‣ Save as or in the Layers panel in the layer’s context menu select Export ‣ Save features as.
Pic. 9.60. Saving vector layer to a file
To save a QGIS style of a vector layer, in the Connect panel open its context menu and select Download as QML.
Pic. 9.61. Saving style to a QML file