The default is the thing to avoid
Under the default regime your gain is spread back across the whole holding period. Each earlier year is taxed at that year's top marginal rate, currently 37%. There is no capital-gains rate and no offsetting deduction. Interest is then added, compounding daily at the IRS underpayment rate.
Almost everything else on the form exists so that you can elect out of this.
The QEF election
A qualified electing fund election taxes you on your share of the fund's income each year, much like a US fund.
It requires the fund to give you an annual information statement in US form. Indian asset managers do not generally produce one, so in practice this election is rarely available.
The mark-to-market election
This taxes you on the paper gain each year as ordinary income. It is available where the shares are regularly traded or redeemable at a published daily net asset value, which most Indian mutual funds are.
It is painful, but far better than the default.
What you will need from the fund
Ask three things in writing before you subscribe, and every year after: does the fund issue a PFIC annual information statement, does it publish a daily NAV, and does it provide any US tax reporting at all.
If the answers are vague, assume the default regime applies and price the investment accordingly.
What to do next
This page explains a rule. It does not work out what you owe, and it is not US tax advice. Take your fund statements to a US CPA or an Enrolled Agent, because the analysis runs per fund, per year.