To work legally in the US you have to have a visa of the correct kind. The USCIS, US Citizen and Immigration Services, issue these visa from their offices in the country or through embassies abroad. Some student visas give the right to work - perhaps only in some professions - and visa overstay or working without the proper permissions can result in deportation and perhaps years of expulsion form the US. Not good if you just got yourself a US boy or girlfriend.
Two central points about US work life: 1) Assume that you don't know anything about how the organizations work, and 2) Americans generally have the impression that Europeans don't work.
On the first point, this is naturally not all true. If you have moved to the US as an intercompany transfer, you probably do know something about how your organization works. But with differences in all areas from the legal aspects - vacation rules, tax withholding, pension plans, medical insurance, discrimination laws, maternity leaves - to communication styles, office layout, breath and depth of the job descriptions, it is prudent to assume that nothing is as you expect. This also applies to organizations who plan to open an affiliate in the US. There is a very steep learning curve and you want to ask for advice before you allocate too much money or hire anybody.
On the second point, there is no legislation related to vacation rules in the US. Consequently any time off given is not a right but a benefit that you negotiate in your contract - except don't expect too much negotiation. The norm among knowledge workers is two weeks paid time off during the first year in the company and that covers vacation, sick leave, children's sick days... Particularly if you have just moved from another continent and are about to meet a new cocktail of local virus it can be stressful that you may have to use all your PTO right away.
If you work for the company long enough your number of PTO days may increase to perhaps four weeks - but if you change jobs it is back to square one. Have in mind that you might expend some of your bargaining power on this front when you negotiate a transfer if you want to have time to visit the old country once in a while - and that you will need to save money for unpaid time off if you get really sick.
Americans are used to open shops all days of the week and at almost all hours. So while they envy the Europeans their loooong vacations, they don't envy us that one consequence of working differently is that public offices and shops generally are open when it is not very convenient for working people. Hence the impression that Europeans don't work.