It's the double sided swing arm.
That will make life a bit easier.
I didn't know what a CB919 looked like until I checked Google. There were sold as
the Hornet 900 on this side of the Atlantic.
I don't think the CB9xx has a centre stand, so you will need a paddock
stand or some way of supporting the bike so that you can remove the
wheel.
Bearings generally don't wear out due to age or mileage. Failures are
usually due to contamination by water and dirt. Once you remove the
outer seal, you will probably find a rusty mess inside.
Bearings are relatively cheap. Any of the big brands should be fine.
I have a preference for Japanese made Koyo bearings, even if they
cost slightly more. IMO, it is better to buy quality bearings from an
industrial bearing suppler rather than a packaged kit with bearings
and seals from a motorcycle shop. Most of the packaged kits come
with Chinese bearings. These are generally ok, but not anywhere
near the quality and durability of the best Japanese bearing makers
like Koyo, NSK, NTN and others.
As Porky said, you can get your local shop to replace the bearings.
If you do it yourself, you will need tools to remove and refit the wheel.
Take note of where the spacers go. Watch out for the spacer between
the sprocket carrier/hub and the wheel.
You will also need a few blocks of wood to support the hub from
underneath while you drift out the bearings. You will need a suitable
drift to drive out the bearings. The first one is tricky because the bearing
spacer sleeve will be in your way. I use a set of large pin punches and
a dangerously heavy lump hammer. Remove the seals and make sure
there isn't a circlip or any other retaining device outside the bearings
before you start.
While you are at it, check the condition of the front wheel and
steering head bearings.
Good Luck.