I have a refurbished galaxy s5. It says verison. Can I use it for usellular

no. they are carrier locked and cannot use any other carrier. only carrier unlocked phones can change between carriers. if u buy a phone in the future, try to get carrier unlocked

The carrier lock isn't the issue here, Verizon 4G/5G phones are unlocked, or get automatically unlocked in 60 days. The issue is the weird bands on some of their phones. Google and Apple have told them to shove it with this crap (Google still bent over perma locking Pixel bootloaders for Verizon, but not the cellular bands), but Samsung and the others bend right over.

Verizon likes to tweak the bands on their Android phones so while they use the same bands as everyone else, they have 1 or 2 which are deprioritized or disabled, or like with 5G, they have their own mmWave band so you can't just bring a phone from AT&T or T-Mobile which was unlocked over and get 5G as a way to extort manufacturers into paying to certify the unlocked version for them and AT&T/T-Mobile, while making carrier locked (now UNlocked) versions somewhat of a gamble they can disclaim responsibility for or refuse to service immediately, or at random and blame you.
Verizon is literally as bad as AT&T with radio tweaks and VoLTE ransoms, as well as being the special kid who has to break from industry standards. In the US, the only one who doesn't pull this garbage is T-Mobile. AT&T is known to be really petty; they tend to make VVM a pain to work on unlocked phones except for iPhones for hopefully obvious reasons.
*Sprint pulled this garbage too, but those policies died with Sprint :-).
**I HAVE had to educate T-Mobile reps that my unlocked iPhone is the same product as theirs since they read the non T-Mobile device flag. They agree with me it's a false flag and it is nothing to worry about, except you own your phone.

However, anything older than the S5 is GENERALLY blocked as many of these Verizon phones did not get officially whitelisted or never supported VoLTE and rely on 3G for voice services which were shutdown with all 3 carriers in the US. The problem with MNVOs is unless they own their network (almost none do, they buy Verizon/AT&T/T-Mo coverage and sell it) or may have some owned coverage but lease network space (basically Dish Network) for most of their network so they have to play ball and block the phones as well for really bad ones, or service these cursed Verizon phones with lesser service quality and also can't tell you it's all because Verizon sucks.