What is PMF

As the title suggests what does Product market fit mean? There is a lot of information and videos about it but I somehow still struggle to understand running a physical product startup. Can someone scale the company to 3-4 million in revenue without it? My startup is very early stage and based on whatever I understand I definitely don’t have it which is making me lose hope like anything. Another question is do those startups work where the problem exists, consumers just don’t know about it, but it’s a serious problem like “Teflon pans causing cancer”