Hardware Sensors Indicator provides temperature, fan and voltage sensor readings within the panel of your desktop.
When running GNOME Shell a shell extension is required to view sensors readings within the top panel. Therefore it is recommended to also install either the KStatusNotifierItem/AppIndicator Support extension https://extensions.gnome.org/extension/615/appindicator-support/, or the Hardware Sensors Indicator extension https://extensions.gnome.org/extension/336/hardware-sensors-indicator/ so that sensor readings are visible.