How do I know dividends from investments? How do I understand how to interpret big difference in income from 2018 to 2019?

If you need assistance and would like an answer on this board, you will have to ask your question with more specificity - more detail.

Otherwise, if you lack a basic understanding of the difference between an investment and a dividend, you might want to consider using TurboTax Live (link below).

https://turbotax.intuit.com/personal-taxes/online/live/

if you don't understand the difference between dividends and investments you should choose between these options:

1) using a full service broker that  charges fees for investment advice

2) not be investing

3) use the web to gain enough knowledge so you do know the difference. 

Dividends are part of investments.  Do you have investments?  Have you bought stocks or mutual funds?  Ask your broker or fund company or financial adviser about it.

Since your loss is limited to $3,000  you can't have a big difference in income from 2018 to 2019 due to losses.

So you must have had a gain to see a big difference from 2018 to 2019.

That's a good thing, right ?