As far as I can tell from the context, the validity for P/ B is exactly one year. I guess this is in reference to Class (PT: Categoria) B in Brazil (D in the USA, at least in the State of Arizona).

Categoria C – habilita a condução de veículo motorizado utilizado em transporte de carga, cujo peso bruto total exceda a três mil e quinhentos quilogramas e utilizado para transporte de até 8 pessoas. Para habilitar-se na categoria C, o condutor deve estar habilitado há, pelo menos, um ano na categoria B e não ter cometido nenhuma infração grave ou gravíssima, nem ser reincidente em infrações médias, durante os últimos doze meses. https://pt.wikipedia.org/wiki/Carteira_Nacional_de_Habilitaç...

Please note: Class B (in Brazil) pertains to the driving of passenger cars. Follow the link above for more information. In the US (or at least in Arizona), it's equivalent to Class D, or "Operator License" (that's what I'm showing in my Driver License). Follow this link for more: https://azdot.gov/motor-vehicles/driver-services/driver-lice...

If the translation is into American English, I suggest localizing to "For Class D". Class B in the US is one of the three types of commercial driver license.

Further research may be needed to confirm that Class D applies equally to other states of the Union.

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Note added at 2 hrs (2021-11-11 00:11:26 GMT)
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Oops. I see now that you are in the UK, so the D classification may not apply at all. I suggest finding the UK equivalent.

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Note added at 2 hrs (2021-11-11 00:19:47 GMT)
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Apparently, the UK terminology is "category B", and encompasses vehicles weighting up to 3,500 kg (which is the same for "Categoria B" in Brazil:

Category B - if you passed your test on or after 1 January 1997
You can drive vehicles up to 3,500kg MAM with up to 8 passenger seats (with a trailer up to 750kg). https://www.gov.uk/driving-licence-categories

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Note added at 2 hrs (2021-11-11 00:20:11 GMT)
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Correction: weighing