If Peter is right, and that's a numeric date-time value...
...then enter into your target cell: "=SourceCell" (for instance, if your original value is in cell A 3, then enter: "=A3" into, say, B 3, or wherever you want the result to go).
And then format the target cell (B 3, or whatever, as per the above) to show only the time. The easiest (? IMO) way to do that is this: Right-click it, select "Format Cells..." from the pop-up menu (it's fourth from the bottom). In the "Format Cells" dialog[ue] that appears, select the (left-most) "Number" tab, and in the "Category" list box on the left, select "Time" (about half-way down on my system). In the "Type" list box on the right, there should be a value like "1:30:55 PM" (at the bottom, on my system); select that, click "OK", and you should be done.
(If you can't find that alternative, you can either futz around with the "Locale (location)" drop-down selector, or switch to the "Custom" category in the list box on the left. The correct Time-category selection seems to be equivalent to putting the value "[$-409]h:mm:ss AM/PM;@" into the "Type" edit line above the list box on the right. I'm not sure what the "[$-409]" and ";@" bits are all about; it seems to me that a simple "h:mm:ss AM/PM" does also work [but that could of course be just on my system].)
HTH!
