Zoho Marketplace is an online business application store with 1000+ ready-to-use extensions for your Zoho products. 

These extensions provide feature enhancements, integrations with third-party software, and many other solutions for common business needs.  In simpler words, Zoho Marketplace is a platform like the Google Playstore where developers can upload their Apps and Extensions and the clients can install it for their organization to enhance their work and to increase productivity.

Navigate to Zoho Marketplace by clicking on the plug icon in the top bar or by clicking on the following  link https://cliq.zoho.com/integrations/marketplace The extensions under Cliq will be listed out.