porcelain wall light Agnes

All light fittings are classified according to their IP value. These IP values (International Protection or Ingress Protection) indicate the degree of protection of the light fitting against dust and moisture. The IP value consists of two digits: the first digit indicates the level of protection against dust; the second, the level of protection against moisture. The higher the IP value, the higher the protection. Check this diagram to see the different existing IP values.

What does IP54 mean?

E27 stands for the type of the fitting of a lamp. E27 stands for a 27 mm diameter thread. "E" stands for Edison thread. So you always have to put an E27 light bulb in a fixture with an E27 fitting. E27 is the standard in England and most European countries.
The early light bulbs (remember them?) had a similar screw thread.
Be careful though, because there are also countries where E26 bulbs are the norm (for example in the United States).
If you would like to know which standard applies in your country, check out this page.
Check out here the complete collection of E27 light bulbs by zangra.