Sounds like the transmission needs to be serviced. Get it checked soon.
It usually means your transmission is going bad. Is there a code (Check engine light on) with the flashing light?
What does A15 mean for a 205 Honda Odyssey
Wat does service code wat mean on a Honda Odyssey
The bulb has broken.
It means the engine has a problem.
Oil Change Time
Its broken.
it means your motor is about too shut down and or is overheating.
Read your owner's manual. Your answer can be found there. But you will find the answer is not there.
The code A123, in your 2008 Honda Odyssey, is a reference that the air filter may need to be changed. A code should reset after changing the air filter.
Transmission has a problem. Take it to a professional.
transmission trouble for sure