Not an economist, but I rather figured it means that markets are regulated in a way that properly allows and encourages competition. No monopolies, no anti-competitive practices, no pricing or wage collusion, no regulatory capture etc. I'm sure this can be interpreted in as many ways as there are special interest groups, though.
E.g, radically, labor markets in the absence of a basic income system are not really free, since employees starve and lose their homes if they do not accept the best available offer. Hence companies' competition for paid labor is not really free, and most groups have an existential threat if they do not accept the terms of the employers that are willing to employ them.
There are a million aspects to this that I'm not an expert in, but many of the "free market" principles are considered in the context of contrasting a market economy vs. a planned economy.
Well, maybe. In common discourse, "free market" is used to downplay the need for government regulation concerning things like labor rights, pollution and anti-consumer/predatory behavior.
E.g, radically, labor markets in the absence of a basic income system are not really free, since employees starve and lose their homes if they do not accept the best available offer. Hence companies' competition for paid labor is not really free, and most groups have an existential threat if they do not accept the terms of the employers that are willing to employ them.
There are a million aspects to this that I'm not an expert in, but many of the "free market" principles are considered in the context of contrasting a market economy vs. a planned economy.