Hello,
It is basically used for show and hide the components.
To add more – aura:renderIf is deprecated as I read on developer.salesforce, use aura:if
<aura:component>
<aura:if isTrue=”{!v.truthy}”>
True
<aura:set attribute=”else”>
False
</aura:set>
</aura:if>
</aura:component>