Property is a general word for anything that belongs to you eg land, buildings, objects. Assets (note that this is a plural term) is used particularly in business and the law. For example, a business's assets could be the total value of the company : its funds, its premises, its stock, its investments, its machinery. Estate is a specific word used in the law in relation to a dead person - everything that the person owned in life, becomes their 'estate'. It can be money, property or 'rights' to use something under copyright or patent.

All these three words are quite similar in meaning, these are things that one can own. But estate is confined only to a piece of land. Asset and property can be a piece of land or other things like car, furniture, clothes etc. We also use the word asset when we talk about somebody's quality eg. her smile is her biggest asset. The word property can also be used to talk about characteristics eg. turmeric has many medicinal properties. Hope it's clear.