Just want to be sure it is safe to use a 25w LED bulb marked as ceiling fan in a regular table lamp.
You can use the bulb in a normal table lamp so long as ...
- Fitting:The fitting is the same (E.g. standard Edison screw in US)
- Voltage: The bulb is marked the same voltage as your household standard voltage (120 V in US). The voltage is approximate, sometimes you will see 110 V - that's a small enough difference that it doesn't matter for our purposes.
- Wattage: The bulb wattage (25W) does not exceed the rating marked on the lamp-holder (unlikely to be a problem for any lamp-holder designed for traditional standard plain ordinary old inefficient incandescent tungsten filament light bulbs like your grandfather used.) Lamp-holders are often marked something like "Max 40W".
- Cooling: There is room for air to flow around the bulb. LED bulbs can overheat in some types of small fully enclosed light fittings. This is unlikely to be a problem in any normal type of table lamp where the shade is open at top and bottom.
Nowadays there are many different types of bulb. Some are designed for 12 V DC instead of 120 or 230 or 240 V AC. We can't see your ceiling fan so we can't be sure it isn't a weird one. That's why you should check markings on the bulb.
Wattage is a guide to how much heat the bulb produces. It is no longer a useful guide to how much light the bulb produces. Sometimes the bulbs are marked with an "equivalent" wattage which you should be careful about understanding - it means "this bulb is roughly as bright as an old-fashioned incandescent tungsten filament bulb that produced this amount of heat". Ignore that and look for the real Wattage. Wattage is really a measure of heat-producing power.
Lumens tells you how much light the bulb produces.