I think horseshoe=shackle
As Chucklz says, the little holes you see are for drainage and are commonly called weep holes. You can read a thread about them here;
viewtopic.php?t=1589&highlight=weep
As for picking them, if it's an Interchangeable Core (IC) padlock, you'll likely find it WAY too hard to pick as a beginner or even early intermediate lock. The existence of multiple shear-lines associated with the control and operating sleeves means that you could be setting all the pins but some are set at one shearline and others set at the other - basically it feels like it should be picked but it won't turn. You can read about making a tool to place tension on just the control sleeve elsewhere on the site if you search for 'IC tension tool'. With one of these tools you can pick to the control sleeve and remove the core from the lock but this of course assumes you're talking about an Best IC padlock which we've yet to determine. See if you can post some pics....
Also, perhaps you could take a quick look at the terminology link before your next question?
viewtopic.php?t=1069&highlight=terminology