From Wikipedia:

"End-of-life" (EOL) is a term used with respect to a product supplied
to customers, indicating that the product is in the end of its useful
life (from the vendor's point of view), and a vendor stops marketing,
selling, or rework sustaining it. (The vendor may simply intend to
limit or end support for the product.)

With this in mind, we can deduce that a Ubuntu version in EOL means that it won't get supported in any way by Canonical. That is, it won't get any updates or support.

But what about a product that is in End of Standard Support?
According to this article made by Canonical,

As Ubuntu LTS releases transition from the standard, public
maintenance window, Extended Security Maintenance (ESM) is available
for organisations with their workloads on Ubuntu LTS releases to
maintain that stability and continuity, ensuring system security and
compliance. With the end of its five-year standard support window in
April, Canonical is announcing the availability of ESM for 14.04
starting 25 April 2019.

ESM for 14.04 provides ongoing kernel security fixes through a secure,
private archive for three years until April 2022. This continued
protection from major security vulnerabilities enables development and
operations teams to plan and manage application upgrades in a failsafe
environment.

ESM is available as a feature of an Ubuntu Advantage subscription.