Which tag should i use to display different text while <apex:commandbutton> is executing versus not executing??

Hi,

Most probably you need a <apex:actionStatus>. A component that displays the status of an AJAX update request. An AJAX request can either be in progress or complete. So you could display different text for start and stop states:

<apex:actionStatus startText=" (incrementing...)" stopText=" (done)" />

See more in https://developer.salesforce.com/docs/atlas.en-us.pages.meta/pages/pages_compref_actionStatus.htm