How to read the sign at a London bus stop

Looking at the sign, in the 1st column, find your destination on the list.
In the next column, find a bus that goes there.
The 3rd and final column has a letter in a circle that tells you which bus stop to stand at to catch that bus.
You'll find a more detailed explanation and photo in Rick's London 2014, page 36-37 of print edition.
The book was indispensable for us on a recent trip to London, maybe you have it, or if not you just might want to buy it.

The first step in mastering London’s bus system is learning how to decipher the bus-stop signs found at major transfer points. The sign lists the various buses that service that neighborhood and the destinations they go to. In the first column, find your destination on the list--e.g., to Paddington Tube/rail station. In the next column, find a bus that goes there--the #23 (routes marked “N” are night-only). In the final column, a letter within a circle (e.g., “H”) tells you exactly which nearby bus stop is yours. Make your way to that stop--you’ll know it’s yours because it will have the same letter on its pole--and wait for the bus with your number to arrive. If the sign says “request stop,” hold your arm out when your bus approaches. Hop on and confirm your destination with the driver . Rick's London book includes photos if that would help your friends. Or--carry a good London map or pick up a free bus map; the most user-friendly is in the free Welcome to London brochure (download it at www.tfl.gov.uk). You can also find more in-depth maps of various sectors of the city (most useful is the Central London Bus Guide). Bus maps are available at Transport for London offices, the City of London TI, and other tourist spots around town.

Thank you both! Exactly what I was looking for.

I'm bookmarking this page for our next trip. I know that the buses in London can be invaluable and I'd love to be able to take better advantage!

Before the internet it was much quicker to solve this kind of problem -- you just asked somebody at the bus stop.

Is it true that London buses no longer accept cash? If not what is the best way to pay for riding the bus for a day or 2 at most.

London buses no longer accept cash.

Choices - Paper Travelcard or Oyster card (with PAYG money) or ticket from streetside machine or Visa card with near field communication on the UK model (not suitable for non British).

So, the best choice is for most tourists to use an Oyster Card with Pay As You Go money loaded on.

According to TfL all American Express contactless cards shouid work, irrespective of country of origin. No USA Mastercards currently will work, and Visa depends on the issuer. An area then where Amex is out in front.

There aren't any streetside machines to buy tickets now either, they've all been shut down. Your ONLY option is an Oyster card, or a pass bought from a tube station.