An LLC should provide a measure of protection for your other investments or personal assets...from liability that occurs related to assets held by the LLC. For example, a tenant of a property held by the LLC sues you. If you are doing business in the name of the LLC they would have to sue the LLC. A couple of caveats and things to consider:
1) you need do do bisiness related to that/those properties under the name of the LLC consistently. Eg. Rental agreement in the name of the LLC. Rent income goes into a bank account in the name of the LLC. Expenses for the property paid for by the LLC. Search on "piercing the veil" for discussion about it, but do not necessarily believe everything. You will get the idea.
2) An LLC does complicate administration of the property. You would file a tax form for the LLC...then the resulting profit goes on a K1 form to inform your personal tax form. In my opinion the extra tax forms is the biggest additional workload over holding the property in your own name. Depending on the state the LLC is set up in, there may be an annual or bi-annual form to file to keep the LLC in good standing, but that is easy.
3) if you are a resident of Canada as I am, and setting up a US entity to hold a property in the US, a US LLC is not a good choice. I use an LLP (Limited Liability Partnership) instead. An LLP has the same liability protection but is set up with the State's Secretary of State instead of the Corporations Commission. The reason that an LLC is not good for Canadian residents is that we do not have the same LLC construct in Canada...so our tax authority would just hear "blah blah Company"..."Oh that must be a Corporation" and potentially disallow the credit for tax paid to the IRS for the LLC against tax due in Canada. Double taxation...not good. One disadvantage of an LLP is that there has to be at least two people to form a partnership.
4) if you don't want the complexity of an LLC or LLP to hold your property, another option is to buy more liability insurance. That won't provide true isolation of liability, but it will provide more coverage to pay for liability.
The bottom line for LLCs or LLPs is that they provide liability protection but do not affect taxation rates. The mechanics of taxation change because there is another tax form to complete, but the tax rates etc are the same as if holding the property personally. That's the difference with a Corporation. A Corporation provides liability protection but the tax rates for rental income and capital gains are higher in most cases.