Ah, you're wanting to provide hyperlink text. That's not what a Placeholder does or is. The Placeholder adds the edit input placeholder attribute to the input. The hyperlink text can only be supplied by the user directly when you've set the web address field parameter "Web Address Type" to "Hypertext and URL". The alternative is to force a different display for the field, which below usage worked in my tests as long as "Web Address Type" is set to "URL Only".
Parameters > Layout > Profile Value Layout
Code:
[cb:if cb_webaddress=""][value][/cb:if]
[cb:if cb_webaddress!=""]<a href="[cb_webaddress]" target="_blank" rel="nofollow">Google Map</a>[/cb:if]
Replace cb_webaddress with the name of your field.