I have the following query
SELECT T0.TxInvPRLote ,T0.TxInvPRProducto ,T0.TxInvPRPeso AS PesoInventarioPR, T1.peso AS PesoDeshuese ,T2.CodBarras_Planta
FROM [dbo].[tblinv_txinventarioPR] T0
INNER JOIN [dbo].[tbldeshuese] T1 ON T0.TxInvPRLote = T1.codlote
INNER JOIN [dbo].[tblarticulos] T2 ON T0.TxInvPRProducto = T2.codigo
WHERE TxInvPRLote ='17732'
which gives me the following result
there are several products like the PT-105 with a weight I need to group this product and add its weight not only is the PT-105 but many more
If what you need is to group that field you just have to group by the product and then add the weight, that way you will get what you need,
example your code should be like this more or less, I hope it works for you,