Cata_bRc, your english is fine, don't worry.

One way you can do that is by using the formula SUMIF. For example:
1) Let's consider you have three sheets (Sheet1, Sheet2 and Sheet3) and a 4th one called Total

2) On Sheet1 you have:
Name | Value
ABC | 10
ABC | 20
DEF | 30
GHI | 40

3) On Sheet2 you have:
Name | Value
ABC | 10
DEF | 20
GHI | 30


4) On Sheet3 you have:
Name | Value
DEF | 10
GHI | 20

Then, on sheet Total you can do the following:
Name | Value
ABC | =SUMIF(Sheet1!A:A,A2,Sheet1!B:B)+SUMIF(Sheet2!A:A,A2,Sheet2!B:B)+SUMIF(Sheet3!A:A,A2,Sheet3!B:B)
DEF | =SUMIF(Sheet1!A:A,A3,Sheet1!B:B)+SUMIF(Sheet2!A:A,A3,Sheet2!B:B)+SUMIF(Sheet3!A:A,A3,Sheet3!B:B)
GHI | =SUMIF(Sheet1!A:A,A4,Sheet1!B:B)+SUMIF(Sheet2!A:A,A4,Sheet2!B:B)+SUMIF(Sheet3!A:A,A4,Sheet3!B:B)

As you can notice that way will required one SUMIF for each sheet on your workbook.

As an alternative you could put all 31 Sheets in a single one (columns: Day, Name, Value) and use a very powerful Excel tool called Pivot Table.