Helm is a tool similar to apt/yum/homebrew for Kubernetes. It is used for managing Kubernetes charts and installing Kubernetes applications. If you deploy applications to Kubernetes, Helm makes it easy to version those deployments, package it, make a release of it, and deploy, delete, upgrade and even rollback those deployments as charts.
A chart is a collection of files that describe a set of Kubernetes resources required for running Kubernetes applications, tools, or services. The relationship between Chart and Helm is similar to that between rpm and yum.
A release is a chart instance running on Kubernetes. A single chart can be installed many times into the same cluster, and create many different releases. Each release can contain one or more Kubernetes resource objects.