How can i open a link directly from an Action.

you mean through a user input task?? please elaborate on this..

No i want to open an external link like www.google.com

i do not think that is possible in appian , you can do that through an User input task although but not from action section.

Using an action, we can trigger a process but we can't open any external links directly using an action. If you want to open any external link from form use safe link. forum.appian.com/.../SAIL_Components.html

I do not know of a way to have an Action link directly to an external site, but you can have the action open to a form and then use a!safelink to link to the external site: forum.appian.com/.../SAIL_Components.html
If you configure the form as a quick task with a timeout then it will not show up in the tasks tab and you will not need to include a button on the form, this way it looks more like a link rather than looking like a form.

@pankajk If your intention is to surface a link and navigate to target location thereafter by making use of the 'Action', then I would like to suggest you to re-consider such requirement, as the intention of Action object is completely different. An 'Action' in Appian is defined as a process model that appears as a link in the 'Actions' tab of the published Application.

So it might be worth considering the work around, for instance, you can build a start form for the process model just with a link on the interface, and without any buttons in order to prevent launching the instance.