Hi Everton Dantas,
There is no double taxation agreement between Brazil and the UK, so income could be taxable in both countries. However, unilateral relief under DT3901 can be applied to interest received.
DT3901 - Double Taxation Relief Manual: Guidance by country: Brazil: Admissible taxes
You will need to review your residence, domicile and whether the remittance basis can be applied. HMRC cannot advise on whether you are UK tax resident for the year or not. You will need to use the Statutory residence test to determine this on your own personal circumstances.
Guidance can be found here
RDR3 Statutory Residence Test
Tax on foreign income
Savings are themselved not taxable, but interest arising from the savings is. Even if you have paid tax on this in Brazil, it may also be taxable in the UK. Where unilateral relief applies, a foreign tax credit can be claimed.
Thank you.