Common symbols around you
double insulated, a.k.a. Class II
"Independent lighting auxiliary"  roughly meaning "lighting power supply not built into the luminaire"
The top symbol is for DC barrel plugs, specifying whether the inside or outside is positie.
The middle line is input, where the squiggly tilde ~ indicates AC.
The third line (output)'s solid and dotted line indicates DC.
Double circle, like a vertical venn diagram, are transformers, with a handful of properties marked. There are more combinations of all the parts this image shows, and further ones (e.g. construction site).
Some of the more commonly seen logos / certification bodies include:
UL (United States)
BSI, also Kitemark (UK)
TÜV (Germany, international)
There are also many testing centers, that may deal with additional health and/or safety and/or environmental concerns, though in most cases it's just country-specific.
You're probably used to the logos for the ones applying to your part of the world.
Certification marks, in the end, represent agreements between manufacturers and (ideally well known) testing centers. (and note there are logos that do not mean that at all)
In most places these are not strictly required for sale(verify), yet certification is quite common for a collection of reasons, like you caring about your safety, for company insurance (liabilitywise), varied indirect regulation (e.g. electrical code, fire regulation, medical safety) effectively only buying certified devices, or self-imposed regulation like caring that your house doesn't burn down and for related insurance.
For some devices (e.g. separate power supplies) you can see more-than-usual certification marks, for practical reasons: e.g. when a large company that has locked down the design so that they can mass produce it, for worldwide sale, without a lot of new certification (certifcation is slow, sort of expensive, and may need periodic recertification).
Best known among them is the "chinese export", a nickname of chinese producers stamping the european CE mark. Often with different, tighter spacing (though some real CE products sometimes do this too for spacing reasons).
A bunch of the above are settled in ISO 7000 / IEC 60417, which also have a lot of markings used around mechanisms, indicatons, and buttons, around cars, audio, production lines.
IP ratings for water and object safety