Kibana dashboard

What is the syntax for applying filters in Kibana dashboard?

Your question wasn't really clear to me but, I have been able to work with the "Lucene syntax" in all of Kibana.

No, actually I got that. Can you help me with something? Apart from visualisation, what other benefits can I get if I use Kibana? Can it help me with context logs?

with kibana, you can create visualizations for any kind of logs you have incoming... In my own usecases, i have used it to combine multiple logs from different devices to make them searchable with one search... (Every company uses a different log format for the same thing they want to display.. using kibana I can display this big amount of logs and show them on my visualizations all combined (yes my focus is on he combining of logs)..

Logstash - does the filtering and stuff (the intelligence?)
Elasticsearch - Database
Kibana - GUI and visualizations

I'm no expert with this, so maybe someone else can explain more uses for Kibana?

Maybe you could try explaining what you want to do (your use case)? Not sure what you mean with context logs..