A fugitive warrant means that a court in another jurisdiction, in this case Indiana, has issued a formal arrest warrant for your person based on charges filed there. When a warrant is entered into the National Crime Information Center database, which is the federal system that law enforcement agencies across the country share, it becomes visible to any officer who runs a name check anywhere in the United States.
When your person was booked in Louisiana, the sheriff's department ran his information through NCIC and the Indiana warrant surfaced. At that point Louisiana placed what is called a detainer on him, which is a formal hold that says do not release this person without notifying us first, and that notification goes to Indiana as well.
What happens next follows a predictable sequence. Louisiana holds him in custody while Indiana decides whether to extradite. For a felony warrant Indiana will almost certainly send law enforcement to pick him up, typically sheriff's deputies from the county where the warrant was issued. They travel to Louisiana, take custody, and transport him back to Indiana to face the charges there.
The timeline for that pickup has no guaranteed deadline. It depends on staffing, scheduling, and how quickly Indiana moves. It could be days or it could be weeks. Whatever time he spends sitting in Louisiana custody waiting for the pickup counts as time served toward whatever comes next in Indiana.
He will need legal representation in Indiana before or immediately after he arrives there. The charges he is facing in Indiana are separate from anything happening in Louisiana and require their own attorney.