I live in France.
A proper meal has at least three courses, sometimes four if you have cheese and dessert, plus coffee afterwards. And yes, it is an event.
I find the difference most noticeable at work. When I worked in London occasionally I used to go for lunch with my colleagues but it was a rarity. Most days I would go out on my own, grab a sandwich or a salad from somewhere and sit in the park. Sometimes if it was raining I would go to the staff canteen and sit on my own reading a book on my Kindle.
In France this is unheard of and would be seen as extremely antisocial. When I am in the office, at around 12 o'clock someone usually announces that they are hungry, and then before too long a group of people go down to the canteen together. Everyone will have at least a main course and a dessert, even if it's only a piece of fruit, and often a starter as well. We take the time to sit together and chat. Afterwards we go to the coffee machine and extend lunch by another 10-15 minutes or so.
When I first arrived I felt like we were spending an enormous amount of time at lunch and on coffee breaks. But I realise now that it is a really important part of the culture and essential for building working relationships with people.
The same applies in a slightly different sense outside the context of work. This really is how French people learn to eat, from birth. Even my son, who is only 14 months old, will have some meat and vegetables for lunch, followed by a piece of bread, a yoghurt and some fruit. This happens at 12 o'clock every day. At 4pm he has what the French call goûter, which for older children is usually some sort of cake, but because he's a baby he has some milk, fruit compote and a little biscuit.
When I have lunch with my in-laws, lunch begins with a drink in the living room - champagne if it is a special occasion, otherwise a soft drink, whisky or port - with some snacks like nuts or cherry tomatoes. Then we move to the dining room where everyone has their allocated place at the table, the table is laid properly for multiple courses with water and wine glasses, and everyone has a cloth napkin. There is a bread basket which is refilled throughout the meal. There is usually a light starter, such as smoked salmon or asparagus. Then there is a main course, which is always meat or fish with a side dish. Then there is cheese, and then dessert. Afterwards we move back to the living room and have coffee and usually a chocolate or two.
Lunch is the biggest meal of the day, but even in the evenings if you're just having leftovers, basic rules will be observed. And it's not uncommon to have a main course, cheese/yoghurt and dessert even on a casual Monday evening. It's just that the main course might be Sunday's leftovers, the cheese is whatever you've got in and the dessert is a piece of fruit. Yoghurt is a staple, and often interchangeable with cheese for a casual meal, but not usually for a more formal meal.