As you mentioned, this new expression is now part of our terminology.
In English, we use the adjective “suppressed”. In French, one could speak of demande réprimée, but we have chosen not to use these words, given their negative connotation.
We speak of non-formation of households when the demand is there, but there isn't enough relatively reasonably priced housing available, whether it's a condominium, a house or whatever. So we're talking about people who, for example, are forced to live with roommates or their parents for a little longer than they would have liked because of the lack of suitable housing, which has consequences. When such housing becomes available, one might think that demand is likely to come solely from demographics, i.e., immigration and normal household formation. However, there is also this demand that has been suppressed over the years, and these people are also coming onto the market. As a result, when the supply of housing increases, the easing of pressure on prices is not as great as expected, given that this stock of some 630,000 households is also waiting for housing.
It's difficult to get an idea of the number of people affected. We'd have to make some assumptions about the average number of people per household, but we can estimate that it's at least two to one. So for 630,000 households, I'd say that easily corresponds to over one million people.