If you look straight down to the right of the tube, there's a 17mm bolt labelled ATF. You need a long socket extension to get it off. Once off, you'll need to move some vacuum tubes around in order to get a long funnel in there.
I Have 2004 Honda Odyssey Ex. Would You Tell Me Where The Plug To Fill Transmission Fluid?
If it is an automatic you probably fill it through the dip stick tube. There are special funnels, available at auto stores, for this function.
I had try to fill into that tube, but the tube too small , that should be another place to fill in, this is a Honda vehicle ( not same like another branch, that they have a large dip stick tube for auto transmission ).