Here's how to understand the name:

* Cu₂: This indicates the presence of two copper ions (Cu⁺) with a +1 charge each.

* S₂O₃²⁻: This is the thiosulfate ion, which has a -2 charge.

Since copper has a +1 charge and thiosulfate has a -2 charge, we need two copper ions to balance the charge of one thiosulfate ion. This leads to the formula Cu₂S₂O₃.