how to read bluetooth UUID?

It's just normal JSON, so decimal. From that link:

76	0x004C	Apple, Inc.

If I look at the first device and take look at the second group of 4 digits

From the 'about bluetooth' page, it's a 128 bit UUID - so you can't just take 16 bits out of it. It's the full thing that is the service name - it's non-standard as you say. A quick google doesn't seem to show anyone's written any code to use it either.

it could mean 'sensor value' (for example ....)?

When it's in advertising like this (it can appear in other ways) it means "when you connect, this device has a sensor value", rather than advertising the sensor value to everyone

if this I understadn it correct - where is the value of it?

You'd have to connect first. There are some examples at https://www.espruino.com/About+Bluetooth+LE#connecting-puck-as-central-

What I'd suggest is using nRF connect app first to connect to the device and figure out what services it has and what the values are. It's a nice user-friendly way to see them.

When you connect you may find a whole bunch more services. What you see being advertised as "cbbfe0e1-f7f3-4206-84e0-84cbb3d09dfc" is probably just the device saying I'm a XYZ so that the relevant app knows which device to connect to.

also if the 4 digits were "0x2A80" that mean that the service was Age?

If it was just those 4 digits then yes. But when it's the whole 128 but UUID it's not.