I know that low light is less than 1wpg - 1.5wpg and that medium light is 1.5wpg - 2.5wpg. My question is lets say i have a 5 galon tank for my plants and i have a 25 watt light, so 5 wpg, is this hight lighting or is more likely medium or low ligthing since it is still a small amount of watts?

Thanks in advance

It would be very high lighting.

So what would be the max of plants that i could have?(is there one)

Do you really have a light that will fit inside the hood of a 5 gallon tank to provide a 5wpg? That's really really high...hanging a 25 watt light over a 5 gallon doesn't count because only a fraction would go inside the tank. If you do, stay with high light plants only. It may be too much for some low lights. Stocking isn't directly correlated with lighting. The types of plants and how many depends on the balance of CO2, lighting, temperature and fertilization. With that high of lighting, you'd probably need a CO2 system, warmer temps, liquid ferts and a specialized plant gravel like flourite. Plants will grow very quickly and will need to be trimmed to keep the tank tidy. I think it is easier for a beginner to maintain a lower light aquarium (1-2wpg) with the appropriate plants and additives.

Thanks a lot for your help, I will take all of this into consideration. Thanks again