I have 2 sheets and I want to correlate one row from the sheet 1 with another from the sheet 2,eventually put the result in a third sheet.how do i do that?I mention that Im noob in using Libre.
Hello @Mihu21,
Since it is unclear from your question how exactly you wish to correlate your Row from Sheet1 to your Row from Sheet2, and which kind of result you want to be put into Sheet3, i’ll give an example of how you can concatenate the cell contents from the entire Row 1 of Sheet1 to the cell contents from the entire Row 2 of Sheet2, and put the result in Row 3 of Sheet3.
- Select the entire Row 3 in Sheet3;
- In the formula bar, type the following formula and then press CTRL+SHIFT+ENTER:
=CONCATENATE(Sheet1.1:1;Sheet2.2:2)
EDIT 2017-09-20
Is no prob, now you can learn how to do both 
For the new case you presented, just copy-paste ( or type ) the following formula into cell A1 from Sheet3, and then press CTRL+SHIFT+ENTER:
=IFNA(INDEX(Sheet2.B1:C4;MATCH(Sheet1.A1:A4;Sheet2.B1:B4;-1));"")
Hi,sorry for being ambiguous.I have made mistakes and tangled row with column.
Let me be clear,I want to compare values from two columns,one from sheet1,another from sheet2,if they are equal,I want to take a value from another column from sheet2,which is on the same row with the value i had compared and group with one of the values which was compared and put them in sheet3 in two different columns side by side.
Ex:
Column A from sheet1 with values:apple,berries,orange,lemon.
Column B from sheet2 with values:grapefruit,berries,watermelon,orange
Column C from sheet2 with the values:5,6,7,4.
grapefruit is on the same row with 5,berries is on the same row with 6,watermelon is on the same row with 7 and so on.
After comparing,in sheet3 I will have in column A:berries,orange and in column B:6,4