Management is the act or process of managing or actually realizing of (the results associated with) a set of objectives that are owned by a single party. This act or process is conducted by (agents that do so on behalf of) this party.
Management is about planning and organizing the budgets and other resources so that they become (and/or remain) available to produce the results of the associated objectives. It includes the specification of timelines (deadlines) for the production, as well as the properties and other characteristics (security, quality, sustainability, etc.) of what is actually being produced/maintained. It also deals with making the tools and policies (e.g. working instructions) available for doing all this. In order to keep tabs on the efficiency of the management process, performance indicators may be developed, i.e. gauges that measure how well the resources are spent in this production/maintenance work are also part of this.
The management of a set of objectives can be implemented as a control process. The control objectives that are needed by this control process would typically come from a policy of the owner of the objectives that are managed.
The purpose for a party of having a management process is that it enables him to efficiently realize (the results associated with) various subset of its objectives, to change the specification of the associated results as needed, and to make sure the results are actually going to be used by itself or some other party.