Welcome to the daily halacha (Jewish law). On Shabbat, halva'ah is not allowed, which means you're not going to lend something to your friend on Shabbat. Why? Because, as Maran (our master) Shulchan Aruch says, it falls under the category of mekach u'mimkar b'Shabbat. You're not allowed to do business on Shabbat. And, as the Chachamim (Sages) say, we consider lending an item on Shabbat to your friend to be included in the category of doing business on Shabbat. This might lead a person to sign on Shabbat, write on Shabbat, or do business on Shabbat. So therefore, halva'ah on Shabbat is not allowed.
However, let's say you need to borrow something from your friend on Shabbat, from your neighbor. You need a chair, you have so many guests, and you need an extra chair, an extra plate, whatever it is. Are you allowed to borrow from your neighbor? Maran Shulchan Aruch and Hacham Ovadia Yosef say that if you go over to your friend and tell him that you need the chair, don't tell him, "Hey, can I borrow the chair? Can you lend me the chair?" Don't say those words. Just say, "Hey, I need a chair. Can I have the chair, please?" Obviously, say it politely. But saying the words "Can you be malveh (lend me)?" or "Can I be shoel (borrow)?" is not allowed on Shabbat. But if you just tell him, "Can I have the chair, please?" then you can borrow from your friend on Shabbat. But don't say, "Can I borrow the chair from you?" or "Can you lend me?" Those words make a difference in halacha. Just say, "Can I have a chair, please? I'm missing a chair." Okay. Obviously, you say it politely, but avoid those words called halva'ah and hash'ileni, which means, "Can I borrow something?" or "Can you lend me something?" Avoid those words. Otherwise, it's allowed on Shabbat.
And etz Hacham Ovadia Yosef, obviously, we're talking about items that are needed on Shabbat. You're not allowed to take something from your neighbor on Shabbat or from your friend if it doesn't have any use on Shabbat. If you need it only after Shabbat, then you're preparing from Shabbat for a weekday, which is not allowed. So you're allowed to take something from your friend on Shabbat if you ask politely, but without saying the words "Can I borrow?" or "Lend me." And it's only if that item is needed for Shabbat, to use it on Shabbat. And obviously, only if it's non-electronic, because if it's Muktzeh (set-aside item) on Shabbat, you're not allowed to touch it.