-browserTimeout specifies the timeout before the browser closes after Selenium becomes idle. For example when your test ends, but you do not call
Both timeout and browsertimeout are documented at: https://github.com/SeleniumHQ/selenium/wiki/Grid2#configuring-timeouts-version-221-required
On the hub, setting the -timeout command line option to "30" seconds
will ensure all resources are reclaimed 30 seconds after a client
crashes. On the hub you can also set -browserTimeout 60 to make the
maximum time a node is willing to hang inside the browser 60 seconds.
This will ensure all resources are reclaimed slightly after 60
seconds. All the nodes use these two values from the hub if they are
set. Locally set parameters on a single node has precedence, it is
generally recommended not to set these timeouts on the node.
For shorting or enlarging wait times for elements have a look at Explicit Waits: http://www.seleniumhq.org/docs/04_webdriver_advanced.jsp You can set the wait timeout there per element you are searching for.
The WebDriver timeouts also do not let you override the default timeouts, do not confuse implicit wait for this. It is advised not to use implicit waits.