I still dont understand

Ok, i'll try to explain using models. The question says that 3/5 of Yana's beads is twice of Tricia's. From this sentence, we know that the total number of beads Yana has is 5 units so we can illustrate this with 5 blocks. The next thing we know is that 3 units out of the 5 units that Yana has is equivalent to twice of Tricia. This means that Tricia only has 1.5 units. We draw 1.5 units for Tricia. To get rid of the fraction, we need to multiply everything by 2 (because 1.5 = 3/2 and 2 is the denominator of 1.5). Multiplying the total number of units Yana and Tricia has by 2, Yana now has a total of 10 units (5 x 2 =10) while Tricia has a total of 3 units (1.5 x 2 = 3). Hence, the ratio Yana: Tricia is 10:3.

I added a new answer to illustrate the above. Hopefully, it's useful. Do tell me what you do not get, if it's still unclear, and i'll try my best to explain it.

Oh that means the 3/5 is Yana. I thought 3 units is yana n 5 units is Tricia

Yeps, 3/5 Yana refers to the beads that Yana has. Do note that 3/5 Yana refers to a portion of Yana's beads, not all of Yana's beads because Yana has a total of 5 units (not just 3).