I have a medium to small lump right above the left side of my ankle on my left leg. it is not painful at all. any ideas of what it is?

I have a medium: It could be a cyst which is filled with fluid and can happen after an injury or almost jello type tissue if you have had it for a while or a lipoma, that consists of fatty tissue , both cause no problems. However, if the lump is getting bigger or is not going away, best to see a podiatrist or a surgeon , get an ultrasound and/or an MRI to find exactly what it is.