what is this electrs:0.9.4? newbie here
That is an electrum server which is a full node that allows electrum light clients to connect to it and verify transactions without storing the full chain. elects is basically a backend for light clients/mobile wallets.
Google is your friend.
I see around 15000 listening node (https://bitnodes.io/)
Is that include the electrum server node?
I would think so. If you klick on a country you can see all the available user agents that are advertised. This can just be changed in the bitcoind conf I believe.
They must not advertise them there, not sure. You shouldn’t be concerned if you are.