Can I book flights directly from Google Flights?

• as Google Flights states in their Help then

When searching for flights on Google, you'll usually have the option to book with an airline or online travel agency by going to their website. In some cases, you'll be able to 'Book on Google', completing your transaction with the airline or travel agency while staying on Google.

and if you do "Book on Google" then

Google will securely pass your traveller and payment details to the airline or online travel agency.

In short - Google Flights in most cases act as the intermediate step between you and the airline/travel agency (match you with the seller).

• 1) If it is single airline/group(Star Alliance, Oneworld, SkyTeam)/code sharing partners then it will be sold under one booking.

2) If it is multiple airlines which don't have any agreements then you will have separate bookings and tickets (and additionally no guarantee to reach your destination if you miss a leg because of delays).

You can manipulate if you want to see the separate flights or not under the tab "More".

You can "in some cases", according to Book flights on Google support page:

When searching for flights on Google, you'll usually have the option to book with an airline or online travel agency by going to their website. In some cases, you’ll be able to "Book on Google," completing your transaction with the airline or travel agency while staying on Google.

How to book flights on Google:

Search for flights on Google.

After selecting a flight, choose the “Book on Google” option, if available.

Enter passenger details, including name, gender, telephone number, birthdate, and email address. Select Continue.

Choose a stored payment method or enter a new one, then select Continue.

Review your personal details and flight itinerary, making sure they’re correct.

If available, under Baggage, review the disclaimer. If you’d like to add baggage to your reservation, select Add bags.

Add the number and type of bags you’d like for each passenger, and click Done.

To process your payment and complete your reservation, select Book.

If you can't see "Book on Google" option then it seems that you have to make a reservation through airline or travel agency.

Google Flight is just a marketplace for airlines and online travel agencies. It lists their flight deals, and help the interested customers to compare and book smartly. Any queries regarding the flight has to be answered by the supplier only. It will be a single ticket.

I tried to book a flight from Columbus Ohio to Cape Town South Africa and was so excited to find a great price on Google Flights, only to be sorely disappointed that I could not book it, but had to call (which I did and there was no way they could book the flights Google was showing) or book through a travel agency (and when I clicked on that link, it just took me to zillions of online flight booking agencies and I had to start my search over from scratch for each agency individually). I won't be using google for this flight, that's for sure! Disappointing ...