verfügbar
available
Ready for use, purchase, or access; obtainable or reachable.
Das gewünschte Produkt ist zurzeit leider nicht verfügbar.
The desired product is unfortunately not available at the moment.

available
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available
Ready for use, purchase, or access; obtainable or reachable.
Das gewünschte Produkt ist zurzeit leider nicht verfügbar.
The desired product is unfortunately not available at the moment.

'Verfügbar' (available) is derived from the verb 'verfügen' (to have at one's disposal / to command). The phrase 'über etwas verfügen' means to have something available or to be able to decide over it. The adjective therefore describes the state of something being available.
Der Manager verfügt über ein hohes Budget.
The manager has a large budget at his disposal.
The adjective is often combined with adverbs that describe the degree of availability. Common combinations are 'sofort verfügbar' (available immediately), 'nicht mehr verfügbar' (no longer available), 'frei verfügbar' (freely available), or 'nur begrenzt verfügbar' (available only in limited quantities).
Die Tickets für das Konzert waren nur begrenzt verfügbar.
The tickets for the concert were only available in limited quantities.
'Verfügbar' is usually used with the verb 'sein' (to be) to describe a state. With the verb 'machen' (to make), you express that you make something accessible.
Alle wichtigen Informationen sind online verfügbar.
All important information is available online.
hand
'etwas zur Hand haben' (to have something at hand) and 'verfügbar' both mean that you can use something. 'zur Hand haben' is more concrete and everyday: something is nearby or quickly reachable, for example a pen, a document, or a tool. 'verfügbar' is more general and also fits things, people, appointments, goods, or information. It does not have to be right next to you. If you mean that you can grab something immediately, 'zur Hand haben' is more natural. If something can generally be used or accessed, 'verfügbar' fits better.

Der gewünschte Artikel ist ab Montag wieder verfügbar.
The item you want will be available again starting Monday.
Für das Telefonat habe ich die Unterlagen zur Hand.
I have the documents at hand for the phone call.