Does the re-distribution change the "administrative distance" to 100?
router ospf 10
redistribute bgp 65530 subnets route-map BGP-TO-OSPF
network 172.16.1.0 0.0.255.255 area 0
router bgp 65510
nei 192.168.10.1 remote-as 65520
route-map BGP-TO-OSPF permit 25
set metric 100
Just to add a bit to what Jon and Giuseppe said, a metric is a concept in routing protocols that is used to measure the desirability of a particular route. It is a general term that measures the "cost" of a route. In OSPF, the lower the metric, the lower the cost, the more desirable the route it is. OSPF uses bandwidth and a ratio to determine the numerical metric of a route.
In eigrp, the metric used to determine desirability of a route is derived from the bandwidth and delay between the router and the destination network. The metric is a numerical result of a mathematical equation.
You need to do some reading on routing protocols, as your question speaks to the very basics.
yes the route-map sets the seed metric for OSPF: the redistributed routes will be seen as O E2 routes with metric 100
to be noted that because no match command is present all BGP routes are redistributed.
the subnets keyword is necessary or OSPF will accept only major networks (A,B, C)
Hope to help
No it does't change the administrative distance. What it does is set the metric of each route that is redistributed to 100.