SET STATISTICS IO

(Source: microsoft.com)

Output item	Meaning
Table	Name of the table.
Scan count	Number of seeks/scans started after reaching the leaf level in any direction to retrieve all the values to construct the final dataset for the output. Scan count is 0 if the index used is a unique index or clustered index on a primary key and you are seeking for only one value. For example WHERE Primary_Key_Column = <value>. Scant count is 1 when you are searching for one value using a non-unique clustered index which is defined on a non-primary key column. This is done to check for duplicate values for the key value that you are searching for. For example WHERE Clustered_Index_Key_Column = <value>. Scan count is N when N is the number of different seek/scan started towards the left or right side at the leaf level after locating a key value using the index key.
logical reads	Number of pages read from the data cache.
physical reads	Number of pages read from disk.
read-ahead reads	Number of pages placed into the cache for the query.
lob logical reads	Number of text, ntext, image, or large value type (varchar(max), nvarchar(max), varbinary(max)) pages read from the data cache.
lob physical reads	Number of text, ntext, image or large value type pages read from disk.
lob read-ahead reads	Number of text, ntext, image or large value type pages placed into the cache for the query.