The travel-restrictions upon entry into Norway have been lifted. The same rules as prior to the corona pandemic now apply.
Prior to travelling to other countries you should familiarize yourself with the rules that applies for the country you are travelling to.
About the COVID-19 certificate
Some countries are still using COVID-19 certificate upon entry and at restaurants for example.
You can find your COVID-19 certificate at helsenorge.no if you live in Norway and have a Norwegian social security number or d-number.
Advice before travelling abroad
If you are going to travel abroad, several things should be considered. You should e.g. check what your travel insurance will cover. If you are going to travel or study in Europe, you should bring your European Health Insurance Card.
Each country have their own rules for entry, and may introduce measures that might have consequences for you as a traveller.
You will need to familiarize yourself with the general travel advice for the country you are travelling to.