If the mp3 logo is next to the CD slot, that means that it can play mp3 files off a CD.
The 2009 car versions of the 2nd-generation Berlingo had an AUX input (probably in the glovebox) as standard until the end of April 2009.
From 1st May 2009 the AUX input was no longer standard except on the top-of-the-range XTR versions, but a USB input was a £200 factory-fit option, combined with Bluetooth.
All versions had a CD player capable of playing mp3 files stored on a CD-R (hence the logo on the head unit)
I suspect the van specifications changed at the same time as the car.
So if your van is built to pre-May specs, it should have an AUX input, probably using a 3.5mm jack.
If it is a May-on spec van, it will not have the AUX input, and will only have the USB input if the original owner specified the USB/Bluetooth option.